2026 already! The winter weather here has really been beautiful and I always enjoy this time of year. Writing this yearly musical retrospective has now become a beloved tradition of mine¹ and I enjoy retracing the year's various events through albums I listened to and concerts I went to. Albums In 2025, I added 141 new albums to my collection, around 60% more than last year's haul. I think this might have been too much? I feel like I didn't have time to properly enjoy all of them and as such, I decided to slow down my acquisition spree sometimes in early December, around the time I normally do the complete opposite. This year again, I bought the vast majority of my music on Bandcamp. Most of the other albums I bought as CDs and ripped them. Concerts In 2025, I went to the following 25 (!!) concerts:

• January 17^th: Uzu, Young Blades, She came to quit, Fever Visions
• February 1^st: Over the Hill, Jail, Mortier, Ain't Right
• February 7^th: B ton Arm , Mulchulation II, Ooz
• February 15^th: The Prowlers, Ultra Razzia, Sistema de Muerte, Trauma Bond
• February 28^th: Francb tards
• March 28^th: Conflit Majeur, to Even Exist, Crachat
• April 12^th: Jetsam, Mortier, NIIVI, Canette
• April 26^th-27^th (Montreal Oi! Fest 2025): The Buzzers, Bad Terms, Sons of Pride, Liberty and Justice, Flafoot 56, The Beltones, Mortier, Street Code, The Stress, Alternate Action
• May 1^st: Bauxite, Atomic threat, the 351's
• May 30^th: Uzu, Tenaz, Extra a Humana, Sistema de muerte
• June 7^th: Ordures Ioniques, Tulaviok, Fucking Raymonds, Voyou
• June 18^th: Tiken Jah Fakoly
• June 21^st: Sa an Supa Celebration
• June 26^th: Taxi Girls, Death Proof, Laura Krieg
• July 4^th: Frente Cumbiero
• July 12^th: Montreal's Big Fiesta DJ Set
• August 16^th: Guerilla Poubelle
• September 11^th: No Suicide Act, Mortier
• September 20^th: Hors Contr le, Union Thugs, Barricade Mentale
• October 20^th: Ezra Furman, The Golden Dregs
• October 24^th: Overbass, Hommage B rurier Noir, Self Control, Vermin Kaos
• November 6^th: B ton Arm , Faze, Slash Need, Chain Block
• November 28^th (Blood Moon Ritual 2025): Bhatt, Channeler, Pyrocene Death Cult, Masse d'Armes
• December 13^th (Stomp Records' 30^th Anniversary Bash): The Planet Smashers, The Flatliners, Wine Lips, The Anti-Queens, Crash ton rock

Although I haven't touched metalfinder's code in a good while, my instance still works very well and I get the occasional match when a big-name artist in my collection comes in town. Most the venues that advertise on Bandsintown are tied to Ticketmaster though, which means most underground artists (i.e. most of the music I listen to) end up playing elsewhere. As such, shout out again to the Gancio project and to the folks running the Montreal instance. It continues to be a smash hit and most of the interesting concerts end up being advertised there. See you all in 2026!

In 2007, Martin Escardo wrote a often-read blog post about Seemingly impossible functional programs . One such seemingly impossible function is find, which takes a predicate on infinite sequences of bits, and returns an infinite sequence for which that predicate hold (unless the predicate is just always false, in which case it returns some arbitrary sequence). Inspired by conversations with and experiments by Massin Guerdi at the dinner of LeaningIn 2025 in Berlin (yes, this blog post has been in my pipeline for far too long), I wanted to play around these concepts in Lean. Let s represent infinite sequences of bits as functions from Nat to Bit, and give them a nice name, and some basic functionality, including a binary operator for consing an element to the front:

import Mathlib.Data.Nat.Find
abbrev Bit := Bool
def Cantor : Type := Nat   Bit
def Cantor.head (a : Cantor) : Bit := a 0
def Cantor.tail (a : Cantor) : Cantor := fun i => a (i + 1)
@[simp, grind] def Cantor.cons (x : Bit) (a : Cantor) : Cantor
    0 => x
    i+1 => a i
infix:60 " # " => Cantor.cons

With this in place, we can write Escardo s function in Lean. His blog post discusses a few variants; I ll focus on just one of them:

mutual
  partial def forsome (p : Cantor   Bool) : Bool :=
    p (find p)
  partial def find (p : Cantor   Bool) : Cantor :=
    have b := forsome (fun a => p (true # a))
    (b # find (fun a => p (b # a)))
end

We define find together with forsome, which checks if the predicate p holds for any sequence. Using that find sets the first element of the result to true if there exists a squence starting with true, else to false, and then tries to find the rest of the sequence. It is a bit of a brian twiter that this code works, but it does:

def fifth_false : Cantor   Bool := fun a => not (a 5)
/-- info: [true, true, true, true, true, false, true, true, true, true] -/
#guard_msgs in
#eval List.ofFn (fun (i : Fin 10) => find fifth_false i)

Of course, in Lean we don t just want to define these functions, but we want to prove that they do what we expect them to do. Above we defined them as partial functions, even though we hope that they are not actually partial: The partial keyword means that we don t have to do a termination proof, but also that we cannot prove anything about these functions. So can we convince Lean that these functions are total after all? We can, but it s a bit of a puzzle, and we have to adjust the definitions. First of all, these seemingly impossible functions are only possible because we assume that the predicate we pass to it, p, is computable and total. This is where the whole magic comes from, and I recommend to read Escardo s blog posts and papers for more on this fascinating topic. In particular, you will learn that a predicate on Cantor that is computable and total necessarily only looks at some initial fragment of the sequence. The length of that prefix is called the modulus . So if we hope to prove termination of find and forsome, we have to restrict their argument p to only such computable predicates. To that end I introduce HasModulus and the subtype of predicates on Cantor that have such a modulus:

-- Extensional (!) modulus of uniform continuity
def HasModulus (p : Cantor    ) :=   n,   a b : Cantor, (  i < n, a i = b i)   p a = p b
@[ext] structure CantorPred where
  pred : Cantor   Bool
  hasModulus : HasModulus pred

The modulus of such a predicate is now the least prefix lenght that determines the predicate. In particular, if the modulus is zero, the predicate is constant:

namespace CantorPred
variable (p : CantorPred)
noncomputable def modulus : Nat :=
  open Classical in Nat.find p.hasModulus
theorem eq_of_modulus :  a b : Cantor, (  i < p.modulus, a i = b i)   p a = p b := by
  open Classical in
  unfold modulus
  exact Nat.find_spec p.hasModulus
theorem eq_of_modulus_eq_0 (hm : p.modulus = 0) :   a b, p a = p b := by
  intro a b
  apply p.eq_of_modulus
  simp [hm]

Because we want to work with CantorPred and not Cantor Bool I have to define some operations on that new type; in particular the cons element before predicate operation that we saw above in find:

def comp_cons (b : Bit) : CantorPred where
  pred := fun a => p (b # a)
  hasModulus := by
    obtain  n, h_n  := p.hasModulus
    cases n with
      zero => exists 0; grind
      succ m =>
      exists m
      intro a b heq
      simp
      apply h_n
      intro i hi
      cases i
        rfl
        grind
@[simp, grind =] theorem comp_cons_pred (x : Bit) (a : Cantor) :
  (p.comp_cons x) a = p (x # a) := rfl

For this operation we know that the modulus decreases (if it wasn t already zero):

theorem comp_cons_modulus (x : Bit) :
    (p.comp_cons x).modulus   p.modulus - 1 := by
  open Classical in
  apply Nat.find_le
  intro a b hab
  apply p.eq_of_modulus
  cases hh : p.modulus
    simp
    intro i hi
    cases i
      grind
      grind
grind_pattern comp_cons_modulus => (p.comp_cons x).modulus

We can rewrite the find function above to use these operations:

mutual
  partial def forsome (p : CantorPred) : Bool := p (find p)
  partial def find (p : CantorPred) : Cantor := fun i =>
    have b := forsome (p.comp_cons true)
    (b # find (p.comp_cons b)) i
end

I have also eta-expanded the Cantor function returned by find; there is now a fun i => i around the body. We ll shortly see why that is needed. Now have everything in place to attempt a termination proof. Before we do that proof, we could step back and try to come up with an informal termination argument.

• The recursive call from forsome to find doesn t decrease any argument at all. This is ok if all calls from find to forsome are decreasing.
• The recursive call from find to find decreases the index i as the recursive call is behind the Cantor.cons operation that shifts the index. Good.
• The recursive call from find to forsome decreases the modulus of the argument p, if it wasn t already zero. But if was zero, it does not decrease it! But if it zero, then the call from forsome to find doesn t actually need to call find, because then p doesn t look at its argument.

We can express all this reasoning as a termination measure in the form of a lexicographic triple. The 0 and 1 in the middle component mean that for zero modulus, we can call forsome from find for free .

mutual
  def forsome (p : CantorPred) : Bool := p (find p)
  termination_by (p.modulus, if p.modulus = 0 then 0 else 1, 0)
  decreasing_by grind
  def find (p : CantorPred) : Cantor := fun i =>
    have b := forsome (p.comp_cons true)
    (b # find (p.comp_cons b)) i
  termination_by i => (p.modulus, if p.modulus = 0 then 1 else 0, i)
  decreasing_by all_goals grind
end

The termination proof doesn t go through just yet: Lean is not able to see that (_ # p) i will call p with i - 1, and it does not see that p (find p) only uses find p if the modulus of p is non-zero. We can use the wf_preprocess feature to tell it about that: The following theorem replaces a call to p f, where p is a function parameter, with the slightly more complex but provably equivalent expression on the right, where the call to f is no in the else branch of an if-then-else and thus has p.modulus = 0 in scope:

@[wf_preprocess]
theorem coe_wf (p : CantorPred) :
    (wfParam p) f = p (if _ : p.modulus = 0 then fun _ => false else f) := by
  split
  next h => apply p.eq_of_modulus_eq_0 h
  next => rfl

And similarly we replace (_ # p) i with a variant that extend the context with information on how p is called:

def cantor_cons' (x : Bit) (i : Nat) (a :   j, j + 1 = i   Bit) : Bit :=
  match i with
    0 => x
    j + 1 => a j (by grind)
@[wf_preprocess] theorem cantor_cons_congr (b : Bit) (a : Cantor) (i : Nat) :
  (b # a) i = cantor_cons' b i (fun j _ => a j) := by cases i <;> rfl

After these declarations, the above definition of forsome and find goes through! It remains to now prove that they do what they should, by a simple induction on the modulus of p:

@[simp, grind =] theorem tail_cons_eq (a : Cantor) : (x # a).tail = a := by
  funext i; simp [Cantor.tail, Cantor.cons]
@[simp, grind =] theorem head_cons_tail_eq (a : Cantor) : a.head # a.tail = a := by
  funext i; cases i <;> rfl
theorem find_correct (p : CantorPred) (h_exists :   a, p a) : p (find p) := by
  by_cases h0 : p.modulus = 0
    obtain  a, h_a  := h_exists
    rw [  h_a]
    apply p.eq_of_modulus_eq_0 h0
    rw [find.eq_unfold, forsome.eq_unfold]
    dsimp -zeta
    extract_lets b
    change p (_ # _)
    by_cases htrue :   a, p (true # a)
    next =>
      have := find_correct (p.comp_cons true) htrue
      grind
    next =>
      have : b = false := by grind
      clear_value b; subst b
      have hfalse :   a, p (false # a) := by
        obtain  a, h_a  := h_exists
        cases h : a.head
          exists Cantor.tail a
          grind
          exfalso
          apply htrue
          exists Cantor.tail a
          grind
      clear h_exists
      exact find_correct (p.comp_cons false) hfalse
termination_by p.modulus
decreasing_by all_goals grind
theorem forsome_correct (p : CantorPred) :
    forsome p   (  a, p a) where
  mp hfind := by unfold forsome at hfind; exists find p
  mpr hex := by unfold forsome; exact find_correct p hex

This is pretty nice! However there is more to do. For example, Escardo has a massively faster variant of find that we can implement as a partial function in Lean:

def findBit (p : Bit   Bool) : Bit :=
  if p false then false else true
def branch (x : Bit) (l r : Cantor) : Cantor :=
  fun n =>
    if n = 0      then x
    else if 2   n then r ((n - 2) / 2)
                  else l ((n - 1) / 2)
mutual
  partial def forsome (p : Cantor -> Bool) : Bool :=
    p (find p)
  partial def find (p : Cantor -> Bool) : Cantor :=
    let x := findBit (fun x => forsome (fun l => forsome (fun r => p (branch x l r))))
    let l := find (fun l => forsome (fun r => p (branch x l r)))
    let r := find (fun r => p (branch x l r))
    branch x l r
end

But can we get this past Lean s termination checker? In order to prove that the modulus of p is decreasing, we d have to know that, for example, find (fun r => p (branch x l r)) is behaving nicely. Unforunately, it is rather hard to do termination proof for a function that relies on the behaviour of the function itself. So I ll leave this open as a future exercise. I have dumped the code for this post at https://github.com/nomeata/lean-cantor.

December 2025 started off with a nice event, namely a small gathering of Vienna based DDs. Some of us were at DebConf25 in Brest and we thought it might be nice to have a get-together of DDs in Vienna. A couple of months after DebConf25 I picked up the idea, let someone else ping the DDs, booked a table at a local cafe and in the end we were a group of 6 DDs. It was nice to put faces to names, names to nicknames and to hear what people are up to. We are definitely planning to repeat that! December also ended with a meeting of nerds: the 39th Chaos Communication Congress in Hamburg. As usual, I did not really have that much time to watch many talks. I tend to bookmark a lot of them in the scheduling app in advance, but once I m at the congress the social aspect is much more important and I try to only attend workshop or talks that are not recorded. Watching the recordings afterward is possible anyway (and I actually try to do that!). There was also a Debian Developers meetup at day 3, combined with the usual time confusion regarding UTC and CET. We talked about having a Debian table at 40c3, so maybe the timezone won t be that much of a problem in the next time. Two talks I recommend are CSS Clicker Training: Making games in a styling language and To sign or not to sign: Practical vulnerabilities in GPG & friends. Regarding package uploads this month did not happen that much, I only uploaded the new version (0.9.3) of labwc. I created two new releases for carl. First a 0.5 release that adds Today and SpecifiedDate as properties. I forwarded an issue about dates not being parsed correctly to the icalendar issue tracker and this was fixed a couple of days later (thanks!). I then created a 0.5.1 release containing that fix. I also started planning to move the carl repository back to codeberg, because Github feels more and more like an AI Slop platform. The work on debiverse also continued. I removed the tailwind CSS framework, and it was actually not that hard to reproduce all the needed CSS classes with custom CSS. I think that CSS frameworks make sense to a point, but once you start implementing stuff that the framework does not provide, it is easier if everything comes out of one set of rules. There was also the article Vanilla CSS is all you need which goes into the same direction and which gave me some ideas how to organize the CSS directives. I also refactored the filter generation for the listing filters and the HTML filter form is now generated from the FastAPI Query Parameter Model. For navigation I implemented a sidebar, that is hidden on small screens but can be toggled using a burger menu. I also stumbled upon An uncomfortable but necessary discussion about the Debian bug tracker, which raises some valid points. I think debiverse could be a solution to the first point of What could be a way forward? , namely: Create a new web service that parses the existing bug data and displays it in a rich format . But if there is ever another way than email to interact with bugs.debian.org, than this approach should not rely on passing on the commands via mail. If I click a button in a web interface to raise the severity, the severity should be raised right away - not 10 minutes later when the email is received. I think the individual parts (web, database, mail interface) should be decoupled and talk to each other via APIs.

I just released mrcal 2.5; much more about that in a future post. Here, I'd like to talk about some implementation details.

Review: This Brutal Moon, by Bethany Jacobs

Series:	Kindom Trilogy #3
Publisher:	Orbit
Copyright:	December 2025
ISBN:	0-316-46373-6
Format:	Kindle
Pages:	497

This Brutal Moon is a science fiction thriller with bits of cyberpunk and space opera. It concludes the trilogy begun with These Burning Stars. The three books tell one story in three volumes, and ideally you would read all three in close succession. There is a massive twist in the first book that I am still not trying to spoil, so please forgive some vague description. At the conclusion of These Burning Stars, Jacobs had moved a lot of pieces into position, but it was not yet clear to me where the plot was going, or even if it would come to a solid ending in three volumes as promised by the series title. It does. This Brutal Moon opens with some of the political maneuvering that characterized These Burning Stars, but once things start happening, the reader gets all of the action they could wish for and then some. I am pleased to report that, at least as far as I'm concerned, Jacobs nails the ending. Not only is it deeply satisfying, the characterization in this book is so good, and adds so smoothly to the characterization of the previous books, that I saw the whole series in a new light. I thought this was one of the best science fiction series finales I've ever read. Take that with a grain of salt, since some of those reasons are specific to me and the mood I was in when I read it, but this is fantastic stuff. There is a lot of action at the climax of this book, split across at least four vantage points and linked in a grand strategy with chaotic surprises. I kept all of the pieces straight and understood how they were linked thanks to Jacobs's clear narration, which is impressive given the number of pieces in motion. That's not the heart of this book, though. The action climax is payoff for the readers who want to see some ass-kicking, and it does contain some moving and memorable moments, but it relies on some questionable villain behavior and a convenient plot device introduced only in this volume. The action-thriller payoff is competent but not, I think, outstanding. What put this book into a category of its own were the characters, and specifically how Jacobs assembles sweeping political consequences from characters who, each alone, would never have brought about such a thing, and in some cases had little desire for it. Looking back on the trilogy, I think Jacobs has captured, among all of the violence and action-movie combat and space-opera politics, the understanding that political upheaval is a relay race. The people who have the personalities to start it don't have the personality required to nurture it or supply it, and those who can end it are yet again different. This series is a fascinating catalog of political actors the instigator, the idealist, the pragmatist, the soldier, the one who supports her friends, and several varieties and intensities of leaders and it respects all of them without anointing any of them as the One True Revolutionary. The characters are larger than life, yes, and this series isn't going to win awards for gritty realism, but it's saying something satisfyingly complex about where we find courage and how a cause is pushed forward by different people with different skills and emotions at different points in time. Sometimes accidentally, and often in entirely unexpected ways. As before, the main story is interwoven with flashbacks. This time, we finally see the full story of the destruction of the moon of Jeve. The reader has known about this since the first volume, but Jacobs has a few more secrets to show (including, I will admit, setting up a plot device) and some pointed commentary on resource extraction economies. I think this part of the book was a bit obviously constructed, although the characterization was great and the visible junction points of the plot didn't stop me from enjoying the thrill when the pieces came together. But the best part of this book was the fact there was 10% of it left after the climax. Jacobs wrote an actual denouement, and it was everything I wanted and then some. We get proper story conclusions for each of the characters, several powerful emotional gut punches, some remarkably subtle and thoughtful discussion of political construction for a series that tended more towards space-opera action, and a conclusion for the primary series relationship that may not be to every reader's taste but was utterly, perfectly, beautifully correct for mine. I spent a whole lot of the last fifty pages of this book trying not to cry, in the best way. The character evolution over the course of this series is simply superb. Each character ages like fine wine, developing more depth, more nuance, but without merging. They become more themselves, which is an impressive feat across at least four very different major characters. You can see the vulnerabilities and know what put them there, you can see the strengths they developed to compensate, and you can see why they need the support the other characters provide. And each of them is so delightfully different. This was so good. This was so precisely the type of story that I was in the mood for, with just the type of tenderness for its characters that I wanted, that I am certain I am not objective about it. It will be one of those books where other people will complain about flaws that I didn't see or didn't care about because it was doing the things I wanted from it so perfectly. It's so good that it elevated the entire trilogy; the journey was so worth the ending. I'm afraid this review will be less than helpful because it's mostly nonspecific raving. This series is such a spoiler minefield that I'd need a full spoiler review to be specific, but my reaction is so driven by emotion that I'm not sure that would help if the characters didn't strike you the way that they struck me. I think the best advice I can offer is to say that if you liked the emotional tone of the end of These Burning Stars (not the big plot twist, the character reaction to the political goal that you learn drove the plot), stick with the series, because that's a sign of the questions Jacobs is asking. If you didn't like the characters at the end (not the middle) of the first novel, bail out, because you're going to get a lot more of that. Highly, highly recommended, and the best thing I've read all year, with the caveats that you should read the content notes, and that some people are going to bounce off this series because it's too intense and melodramatic. That intensity will not let up, so if that's not what you're in the mood for, wait on this trilogy until you are. Content notes: Graphic violence, torture, mentions of off-screen child sexual assault, a graphic corpse, and a whole lot of trauma. One somewhat grumbly postscript: This is the sort of book where I need to not read other people's reviews because I'll get too defensive of it (it's just a book I liked!). But there is one bit of review commentary I've seen about the trilogy that annoys me enough I have to mention it. Other reviewers seem to be latching on to the Jeveni (an ethnic group in the trilogy) as Space Jews and then having various feelings about that. I can see some parallels, I'm not going to say that it's completely wrong, but I also beg people to read about a fictional oppressed ethnic and religious minority and not immediately think "oh, they must be stand-ins for Jews." That's kind of weird? And people from the US, in particular, perhaps should not read a story about an ethnic group enslaved due to their productive skill and economic value and think "they must be analogous to Jews, there are no other possible parallels here." There are a lot of other comparisons that can be made, including to the commonalities between the methods many different oppressed minorities have used to survive and preserve their culture. Rating: 10 out of 10

I guess it is about time I posted a new summary of the free software and open culture activites and projects I have been involved in the last year. The days have been so packed the last year that I have failed with my intention to post at least one blog post per month, so this summary became rather long. I am sorry about this. This year was the year I got tired of the lack of new releases of the multimedia related libraries published via Xiph, and I decided to wrap up the current state and make the releases myself. In a burst of activity early this year, I collected and tested patches, coordinated with other developers and finally made new tarballs and release announcement for theora, and new tarball releases for liboggz, kate and fishsound. This upstreamed several patches accumulated in Debian and other Linux distributions for the last 15 years or so. To change the world and the future, it is important to start with the kids, and one such avenue of change have been created by the current president of FSF Europe, Matthias Kirschner. He wrote a book for children, Ada & Zangemann, and I have been involved in its translation framework for the entire year. The source code has been transformed to Docbook and I have been conducting and coordinating translations into Norwegian Bokm l and Nynorsk, as well as preparing paper editions of the book and an animation movie with Norwegian voices. The Bokm l edition is very close to ready, and will be available early in 2026, and the movie release will follow shortly after this. I intend announce this on my blog and elsewhere when this happen. Please get in touch if you want to help spread the word about this book in Norwegian. I hope we can get the author to Norway when making the Norwegian releases. This year I continued a push for the system I made a few years ago to improve hardware dongle handling on Linux. The Isenkram system use hardware mapping information provided by relevant packages using the AppStream system to propose which Linux distribution packages to install on a given machine to support dongles like cameras, finger print readers, smart card readers, LEGO controllers, ECC memory and other hardware. I have followed up on the list of packages providing such mapping, either to get it into Debian or to upstream the necessary metadata. I am not sure if we are at a point where package maintainers on their own add such information to their packages, but there are Debian lintian reports suggesting it and I have send patches to all packages I am aware of that should include such mappings. Most of the patches are included in Debian now, only 27 was left the last time I checked. As part of my involvement with Debian, I continued my push to get all orphaned packages without a version control repository migrated to git. I am not sure how many packages I went through, but it was in the range of 200-300 packages. In addition to this I updated, sponsored, pushed maintainers for updates upstreamed patches for and fixed RC issues with battery-stats, bs1770gain, isenkram, libonvif, mfiutil, opensnitch, simplescreenrecorder, vlc-plugin-bittorrent and wakeonlan. I've also followed up LEGO related packages, dahdi support for Asterisk, llama.cpp and whisper.cpp in particular for the AMD GPU I was donated by AMD, as well as tried yet again to convince the upstream developers of the photogrammetric workstion e-foto to get their program into a state that could be included in Debian. As I do not buy into the story that it is great to expose oneself to the whims of and priorities of commercial entities to have access to cultural expressions like films and music, I still maintain a huge collection of movies. For this to work well, I have ended up as part of the people maintaining lsdvd upstream and wrapped up a new release fixing several crash bugs caused by DVDs with intentionally broken metadata, and introduced code to list a DVD ID in the lsdvd output. Related to this, I have also worked some add-ons for my main video and music player, and took over upstream maintenance of the Invidious add-on, which sadly stopped working for non-authenticated users when web scrapers made it impossible for Invidious installations to provide a open API, as well as contributed to the NRK and projector control add-ons. As part of my involvement in the Norwegian archiving community and standardisation work, we organised a Noark 5 workshop this spring discussing how to decide what to keep and what to delete in digital archives. We finally managed to apply for Noark 5 certification for the free software archive API Nikita, as well as worked to test and improve the performance of Nikita together with people on my day job at the university. Manufacturing using Free Software is still a focus for me, and I have continued my involved with the LinuxCNC community, organising a developer gathering this summer with the help and sponsoring from the initial start in 2023 from NUUG Foundation and sponsoring from Debian and Redpill-Linpro. We plan to repeat the event also in 2026, but this time NUUG Foundation have told us they do not want a role, so we have found another friendly organisation to handle the money. A popular machine controller with LinuxCNC is the MESA set of electronics, which is centred around a FPGA which now can be programmed using only Free Software. We discussed during this summers gathering how hard it would be to compile the current FPGA source using a Free Software tool chain, and I started looking into this, locating tools to transform the VHDL source into something the Yosys tool chain can handle. Still lot to do there, and I hope to get further next year. An important part of Free Software manufacturing is the ability to design parts and create programs that can be passed to machines making parts, also known as CAD/CAM. The most prominent project for this is FreeCAD, and I have been both pushing to get opencamlib integrated with it in Debian as well as fixing bugs in the handling of Fanuc controlled machines, do make it easier to generate instructions for machines I have access to. I expect to also continue this also next year. This year the UN conference Internet Governance Forum (IGF) was held in Norway, and I tried my best to get a stand for the Norwegian Unix Users Group (NUUG) there. Sadly the effort failed, due to lack of interest with the NUUG Board, but I was happy to see several members at least attend some of the activities related to IGF. Sadly to participate at IGF one need to hand over quite private information, so I decided not to participate in any of the closed forum events myself. Related to NUUG I have been a member of the election board proposing board member candidates to the general assembly, and been part of the program committee of the "Big Tech m vekk" (Big Tech must go away) festival organised by Attac in concert with NUUG and EFN. I've also assisted the Norwegian open TV channel Frikanalen with access to their machines located in a machine room at the university. Related to the University, I have become involved in a small team of students working to build and program robots for the Robocup@Home competition. For 2026 we also plan to use the new features of FreeCAD to make parts for the open hardware robot arm OpenArm. This is also the group that will handle the money for the LinuxCNC gathering in 2026. Also related to the university I was looking into the Linux security auditing system Falco earlier this year, making improvements to the detection rules. This activity is on hold at the moment, and do not expect to continue with this in 2026. I will most likely have to cut down a bit on my free software and open culture activities going forward, as NUUG Foundation, who have funded one day a week for such activities for several years no, sadly have decided they do not want to continue doing this. I am very grateful for their contributions over the years, both with freeing up time for me and supporting several events and projects where I have been involved or taken the initiative on. Now they are reorganizing with more focus on paperwork and applications. As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

Here are my favourite books and movies that I read and watched throughout 2025.

Books

Eliza Clark: Boy Parts (2020)Rachel Cusk: The Outline Trilogy (2014 2018)Edith Wharton: The House of Mirth (1905)Michael Finkel: The Art Thief (2023)Tony Judt: When the Facts Change: Essays 1995-2010 (2010)Jennette McCurdy: I'm Glad My Mom Died (2022)Joan Didion: The Year of Magical Thinking (2005)Jill Lepore: These Truths: A History of the United States (2018)

Films Recent releases

• Marty Surpreme (Josh Safdie, 2023)
• On Becoming a Guinea Fowl (Rungano Nyoni, 2024)
• April (Dea Kulumbegashvili, 2024)
• Nickel Boys (RaMell Ross, 2024)
• Color Book (David Fortune, 2024)
• Blue Road: The Edna O Brien Story (Sin ad O Shea, 2024)

Disappointments this year included 28 Years Later (Danny Boyle, 2025), Cover-Up (Laura Poitras & Mark Obenhaus, 2025), Bugonia (Yorgos Lanthimos, 2025) and Caught Stealing (Darren Aronofsky, 2025).
Older releases ie. Films released before 2024, and not including rewatches from previous years.

• Where Is the Friend's House? (Abbas Kiarostami, 1987)
• Naked (Mike Leigh, 1993)
• The Florida Project (Sean Baker, 2017)
• Taste of Cherry (Abbas Kiarostami, 1997)
• The House of Mirth (Terence Davies, 2000)
• A Summer's Tale ( ric Rohmer, 1996)
• It's Such a Beautiful Day (Don Hertzfeldt, 2012)
• La Haine (Mathieu Kassovitz, 1995)
• The Piano Teacher (Michael Haneke, 2001)
• A Touch of Zen (King Hu, 1970)
• The Taking of Pelham One Two Three (Joseph Sargent, 1974)
• An Affair to Remember (Leo McCarey, 1957)

Distinctly unenjoyable watches included War of the Worlds (Rich Lee, 2025), Highest 2 Lowest (Spike Lee, 2025), Elizabethtown (Cameron Crowe, 2005), Crazy Rich Asians (Jon M. Chu, 2018) and Spinal Tap II: The End Continues (Rob Reiner, 2025). On the other hand, unforgettable cinema experiences this year included big-screen rewatches of Chinatown (Roman Polanski, 1974), Koyaanisqatsi (Godfrey Reggio, 1982), Heat (Michael Mann, 1995) and Night of the Hunter (Charles Laughton, 1955).

Debusine is a tool designed for Debian developers and Operating System developers in general. This post describes how Debusine stores and manages files. Debusine has been designed to run a network of workers that can perform various tasks that consume and produce artifacts . The artifact itself is a collection of files structured into an ontology of artifact types. This generic architecture should be suited to many sorts of build & CI problems. We have implemented artifacts to support building a Debian-like distribution, but the foundations of Debusine aim to be more general than that. For example a package build task takes a debian:source-package as input and produces some debian:binary-packages and a debian:package-build-log as output. This generalized approach is quite different to traditional Debian APT archive implementations, which typically required having the archive contents on the filesystem. Traditionally, most Debian distribution management tasks happen within bespoke applications that cannot share much common infrastructure.

File Stores Debusine s files themselves are stored by the File Store layer. There can be multiple file stores configured, with different policies. Local storage is useful as the initial destination for uploads to Debusine, but it has to be backed up manually and might not scale to sufficiently large volumes of data. Remote storage such as S3 is also available. It is possible to serve a file from any store, with policies for which one to prefer for downloads and uploads. Administrators can set policies for which file stores to use at the scope level, as well as policies for populating and draining stores of files.

Artifacts As mentioned above, files are collected into Artifacts. They combine:

• a set of files with names (including potentially parent directories)
• a category, e.g. debian:source-package
• key-value data in a schema specified by the category and stored as a JSON-encoded dictionary.

Within the stores, files are content-addressed: a file with a given SHA-256 digest is only stored once in any given store, and may be retrieved by that digest. When a new artifact is created, its files are uploaded to Debusine as needed. Some of the files may already be present in the Debusine instance. In that case, if the file is already part of the artifact s workspace, then the client will not need to re-upload the file. But if not, it must be reuploaded to avoid users obtaining unauthorized access to existing file contents in another private workspace or multi-tenant scope. Because the content-addressing makes storing duplicates cheap, it s common to have artifacts that overlap files. For example a debian:upload will contain some of the same files as the related debian:source-package as well as the .changes file. Looking at the debusine.debian.net instance that we run, we can see a content-addressing savings of 629 GiB across our (currently) 2 TiB file store. This is somewhat inflated by the Debian Archive import, that did not need to bother to share artifacts between suites. But it still shows reasonable real-world savings.

APT Repository Representation Unlike a traditional Debian APT repository management tool, the source package and binary packages are not stored directly in the pool of an APT repository on disk on the debusine server. Instead we abstract the repository into a debian:suite collection within the Debusine database. The collection contains the artifacts that make up the APT repository. To ensure that it can be safely represented as a valid URL structure (or files on disk) the suite collection maintains an index of the pool filenames of its artifacts. Suite collections can combine into a debian:archive collection that shares a common file pool. Debusine collections can keep an historical record of when things were added and removed. This, combined with the database-backed collection-driven repository representation makes it very easy to provide APT-consumable snapshot views to every point in a repository s history.

Expiry While a published distribution probably wants to keep the full history of all its package builds, we don t need to retain all of the output of all QA tasks that were run. Artifacts can have an expiration delay or inherit one from their workspace. Once this delay has expired, artifacts which are not being held in any collection are eligible to be automatically cleaned up. QA work that is done in a workspace that has automatic artifact expiry, and isn t publishing the results to an APT suite, will safely automatically expire.

Daily Vacuum A daily vacuum task handles all of the file periodic maintenance for file stores. It does some cleanup of working areas, a scan for unreferenced & missing files, and enforces file store policies. The policy work could be copying files for backup or moving files between stores to keep them within size limits (e.g. from a local upload store into a general cloud store).

In Conclusion Debusine provides abstractions for low-level file storage and object collections. This allows storage to be scalable beyond a single filesystem and highly available. Using content-addressed storage minimizes data duplication within a Debusine instance. For Debian distributions, storing the archive metadata entirely in a database made providing built-in snapshot support easy in Debusine.

Here s my monthly but brief update about the activities I ve done in the FOSS world.

Debian

Whilst I didn t get a chance to do much, here are still a few things that I worked on:

• Prepared security update for wordpress for trixie and bookworm.
• A few discussions with the new DFSG team, et al.
• Assited a few folks in getting their patches submitted via Salsa.
• Mentoring for newcomers.
• Moderation of -project mailing list.

---

Ubuntu

I joined Canonical to work on Ubuntu full-time back in February 2021. Whilst I can t give a full, detailed list of things I did, here s a quick TL;DR of what I did:

• Successfully released Resolute Snapshot 2!
  • This one was also done without the ISO tracker and cdimage access.
  • I think this one went rather smooth. Let s see what we re able to do for snapshot 3.
• Worked on removing GPG keys from the cdimage instance. That took a while, whew!
• Assisted a bunch of folks with my Archive Admin and Release team hats to:
  • review NEW packages for Ubuntu Studio.
  • remove old binaries that are stalling transition and/or migration.
  • LTS requalification of Ubuntu flavours.
  • bootstrapping dotnet-10 packages for Stable Release Updates.
• With that, we ve entered the EOY break. :)
  • I was anyway on vacation for majority of this month. ;)

---

Debian (E)LTS

This month I have worked 72 hours on Debian Long Term Support (LTS) and on its sister Extended LTS project and did the following things:

Released Security Updates

• ruby-git: Multiple vulnerabilities leading to command line injection and improper path escaping.
  • [LTS]: Fixed CVE-2022-25648, CVE-2022-46648, and CVE-2022-47318 via 1.7.0-1+deb11u1 for bullseye. This has been released as DLA 4406-1.
• ruby-sidekiq: Multiple vulnerabilities leading to Cross-site Scripting (XSS) and Denial of Service in Web UI.
  • [LTS]: Fixed CVE-2021-30151 and CVE-2022-23837 via 6.0.4+dfsg-2+deb11u1 for bullseye. This has been released as DLA 4407-1.
• python-apt: Vulnerability leading to crash via invalid nullptr dereference in TagSection.keys().
  • [LTS]: Fixed CVE-2025-6966 via 2.2.1.1 for bullseye. This has been released as DLA 4408-1.
  • [ELTS]: Fixed CVE-2025-6966 via 1.8.4.4 for buster and 1.4.4 for stretch. This has been released as ELA 1596-1.
  • All of this was coordinated b/w the Security team and Julian Andres Klode. Julian will take care of the stable uploads.
• node-url-parse: Vulnerability allowing authorization bypass through specially crafted URL with empty userinfo and no host.
  • [LTS]: Fixed CVE-2022-0639 via 1.5.3-1+deb11u3 for bullseye. This has been released as DLA 4413-1.
• wordpress: Multiple vulnerabilities in WordPress core, leading to Sent Data & Cross-site Scripting.
  • [stable]: Fixed CVE-2025-58674 and CVE-2025-58246 via 6.8.3+dfsg1-0+deb13u1 for trixie. This has been released as DSA 6091-1.
• usbmuxd: Privilege escalation vulnerability via path traversal in SavePairRecord command.
  • [LTS]: Fixed CVE-2025-66004 via 1.1.1-2+deb11u1 for bullseye. This has been released as DLA 4417-1.
  • [ELTS]: Fixed CVE-2025-66004 via 1.1.1~git20181007.f838cf6-1+deb10u1 for buster and 1.1.0-2+deb9u1 for stretch. This has been released as ELA 1599-1.
  • All of this was coordinated b/w the Security team and Yves-Alexis Perez. Yves will take care of the stable uploads.
• gst-plugins-good1.0: Multiple vulnerabilities in isomp4 plugin leading to potential out-of-bounds reads and information disclosure.
  • [LTS]: Fixed CVE-2025-47219 and CVE-2025-47183 via 1.18.4-2+deb11u4 for bullseye. This has been released as DLA 4419-1.
• postgresql-13: Multiple vulnerabilities including unauthorized schema statistics creation and integer overflow in libpq allocation calculations.
  • [LTS]: Fixed CVE-2025-12817 and CVE-2025-12818 via 13.23-0+deb11u1 for bullseye. This update has been prepared by the maintainer, Christoph Berg, and released as DLA 4420-1.
• gst-plugins-base1.0: Multiple vulnerabilities in SubRip subtitle parsing leading to potential crashes and buffer issues.
  • [ELTS]: Fixed CVE-2025-47806, CVE-2025-47807, and CVE-2025-47808 via 1.14.4-2+deb10u5 for buster and 1.10.4-1+deb9u6 for stretch. This has been released as ELA 1600-1.

Work in Progress

• ceph: Affected by CVE-2024-47866, using the argument x-amz-copy-source to put an object and specifying an empty string as its content leads to the RGW daemon crashing, resulting in a DoS attack.
  • [LTS]: Whilst the patch is straightforward, backports are a bit tricky. Also trying to backport the fix for CVE-2022-0670. The update has been prepared as of December 16th and awaiting Thomas Goirand s review.
    • Git repository for bullseye: https://salsa.debian.org/lts-team/packages/ceph/-/tree/debian/bullseye.
  • [ELTS]: Same as LTS - I ve tested the update but waiting for Thomas to ack the LTS upload and so I can proceed with ELTS uploads.
    • Git repository for buster: http://salsa.debian.org/lts-team/packages/ceph/-/commits/debian/buster
    • Git repository for stretch: http://salsa.debian.org/lts-team/packages/ceph/-/commits/debian/stretch
• knot-resolver: Affected by CVE-2023-26249, CVE-2023-46317, and CVE-2022-40188, leading to Denial of Service.
  • [LTS]: The patches aren t very trivial, with CVE-2023-46317 reverting much of the patch for CVE-2023-26249. And then it had to be re-adjusted a bit for v5.3.1. The backports are ready as of December 23rd and awaiting Jakub or Santiago s review.
    • Git repository for bullseye: https://salsa.debian.org/lts-team/packages/knot-resolver/-/tree/debian/bullseye
• adminer: Affected by CVE-2023-45195 and CVE-2023-45196, leading to SSRF and DoS, respectively.
  • [ELTS]: I picked it up again and the patches were already ready in Git. I ve reached out to Alexandre for a quick review and smoke test before we can release it for buster.
    • Git repository for buster: https://salsa.debian.org/lts-team/packages/adminer/-/tree/debian/buster
• u-boot: Affected by CVE-2025-24857, where boot code access control flaw in U-Boot allowing arbitrary code execution via physical access.
  • [ELTS]: As it s only affected the version in stretch, I ve started the work to find the fixing commits and prepare a backport. Not much progress there, I ll roll it over to January.
• ruby-rack: There were multiple vulnerabilities reported in Rack, leading to DoS (memory exhaustion) and proxy bypass.
  • [ELTS]: After completing the work for LTS myself, Bastien picked it up for ELTS and reached out about an upstream regression and we ve been doing some exchanges. Bastien has done most of the work backporting the patches but needs a review and help backporting CVE-2025-61771.

Other Activities

• Frontdesk from 01-12-2025 to 07-12-2025.
  • Auto EOL d a bunch of packages.
  • Marked CVE-2025-12084/python2.7 as end-of-life for bullseye, buster, and stretch.
  • Marked CVE-2025-12084/jython as end-of-life for bullseye.
  • Marked CVE-2025-13992/chromium as end-of-life for bullseye.
  • Marked apache2 CVEs as postponed for bullseye, buster, and stretch.
  • Marked CVE-2025-13654/duc as postponed for bullseye and buster.
  • Marked CVE-2025-32900/kdeconnect as ignored for bullseye.
  • Marked CVE-2025-12084/pypy3 as postponed for bullseye.
  • Marked CVE-2025-14104/util-linux as postponed for bullseye, buster, and stretch.
  • Marked several CVEs for fastdds as postponed for bullseye.
  • Marked several CVEs for pytorch as postponed for bullseye.
  • Marked CVE-2025-2486/edk2 as postponed for bullseye.
  • Marked CVE-2025-6172 7,9 /golang-1.15 as postponed for bullseye.
  • Marked CVE-2025-65637/golang-logrus as postponed for bullseye.
  • Marked CVE-2025-12385/qtdeclarative-opensource-src ,gles as postponed for bullseye, buster, and stretch.
  • Marked TEMP-0000000-D08402/rust-maxminddb as postponed for bullseye.
  • Added the following packages to d,e la-needed.txt:
    • liblivemedia, sogo.
  • During my triage, I had to make the bin/elts-eol script robust to determine the lts_admin repository - did a back and forth with Emilio about this on the list.
  • I sent a gentle reminder to the LTS team about the issues fixed in bullseye but not in bookworm via mailing list: https://lists.debian.org/debian-lts/2025/12/msg00013.html.
• I claimed php-horde-css-parser to work on CVE-2020-13756 for buster and did almost all the work only to realize that the patch already existed in buster and the changelog confirmed that it was intentionally fixed.
  • After speaking with Andreas Henriksson, we figured that the CVE ID was missed when the ELA was generated and so I fixed that via 87afaaf19ce56123bc9508d9c6cd5360b18114ef and 5621431e84818b4e650ffdce4c456daec0ee4d51 in the ELTS security tracker to reflect the situation.
• Participated in a thread which I started last month around using Salsa CI for E/LTS packages and if we plan to sunset it in favor of using Debusine. The plan for now is to keep it around as it s still beneficial and Debusine is still in its early phase.
• Did a lot of back and forth with Helmut about debusine uploads on #debian-elts.
  • While debugging a failure in dcut uploads, I ran into an SSH compatibility issue on deb-master.freexian.com that could be fixed on the server-side. I shared all my findings to Freexian s sysadmin team.
  • A minimal fix on the server side would be one of:

    PubkeyAcceptedAlgorithms -ssh-dss
    

    or explicitly restricting to modern algorithms, e.g.:

    PubkeyAcceptedAlgorithms
    ssh-ed25519,ecdsa-sha2-nistp256,rsa-sha2-512,rsa-sha2-256
    

• Jelly on #debian-lts reported that all my DLA mails had broken GMail s DKIM signature. So I set up sending replies from @debian.org and that seems to have fixed that! \o/
• [LTS] Attended a rather short monthly LTS meeting on Jitsi. Summary here.
• [E/LTS] Monitored discussions on mailing lists, IRC, and all the documentation updates.

---

Until next time.
:wq for today.

Trixie ships Gimp 3.0.4 and the 3.x series has gotten incompatible to XSane, the common frontend for scanners on Linux. Hence the maintainer, J rg Frings-F rst, has disabled the Gimp integration temporarily in response to a Debian bug #1088080. There seems to be no tracking bug for getting the functionality back but people have been commenting on Debian bug #993293 as that is ... loosely related . There are two options to get the Scanning functionality back in Trixie until this is properly resolved by an updated XSane in Debian (e.g. via trixie-backports): Lee Yingtong Li (RunasSudo) has created a Python script that calls XSane as a cli application and published it at https://yingtongli.me/git/gimp-xsanecli/. This worked okish for me but needed me to find the scan in /tmp/ a number of times. This is a good stop-gap script if you need to scan from Gimp $now and look for a quick solution. Upstream has completed the necessary steps to get XSane working as a Gimp 3.x plugin at https://gitlab.com/sane-project/frontend/xsane. Unfortunately compiling this is a bit involved but I made a version that can be dropped into /usr/local/bin or $HOME/bin and works alongside Gimp and the system-installed XSane. So:

1. sudo apt install gimp xsane
2. Download xsane-1.0.0-fit-003 (752kB, AMD64 executable for Trixie) and place it in /usr/local/bin (as root)
3. sha256sum /usr/local/bin/xsane-1.0.0-fit-003
   # result needs to be af04c1a83c41cd2e48e82d04b6017ee0b29d555390ca706e4603378b401e91b2
4. sudo chmod +x /usr/local/bin/xsane-1.0.0-fit-003
5. # Link the executable into the Gimp plugin directory as the user running Gimp:
   mkdir -p $HOME/.config/GIMP/3.0/plug-ins/xsane/
ln -s /usr/local/bin/xsane-1.0.0-fit-003 $HOME/.config/GIMP/3.0/plug-ins/xsane/
6. Restart Gimp
7. Scan from Gimp via File Create Acquire XSane

The source code for the xsane executable above is available under GPL-2 at https://gitlab.com/sane-project/frontend/xsane/-/tree/c5ac0d921606309169067041931e3b0c73436f00. This points to the last upstream commit from 27. September 2025 at the time of writing this blog article.

During my PhD, on a sunny summer s day, I copied some papers to read onto an iPad and cycled down to an outdoor cafe next to the beach. armed with a coffee and an ice cream, I sat and enjoyed the warmth. The only problem was that due to the bright sunlight, I couldn t see a damn thing. In 2021 I decided to take the plunge and buy the Remarkable 2 that has been heavily advertised at the time. Over the next four or so years, I made good use of it to read papers; read drafts of my own papers and chapters; read a small number of technical books; use as a daily planner; take meeting notes for work, PhD and later, personal matters. I didn t buy the remarkable stylus or folio cover instead opting for a (at the time, slightly cheaper) LAMY AL-star EMR. And a fantastic fabric sleeve cover from Emmerson Gray. I installed a hack which let me use the Lamy s button to activate an eraser and also added a bunch of other tweaks. I wouldn t recommend that specific hack anymore as there are safer alternatives (personally untested, but e.g. https://github.com/isaacwisdom/RemarkableLamyEraser) Pros: the writing experience is unparalleled. Excellent. I enjoy writing with fountain pens on good paper but that experience comes with inky fingers, dried up nibs, and a growing pile of paper notebooks. The remarkable is very nearly as good without those drawbacks. Cons: lower contrast than black on white paper and no built in illumination. It needs good light to read. Almost the opposite problem to the iPad! I ve tried a limited number of external clip on lights but nothing is frictionless to use. The traditional two-column, wide margin formatting for academic papers is a bad fit for the remarkable s size (just as it is for computer display sizes. Really is it good for anything people use anymore?). You can pinch to zoom which is OK, or pre-process papers (with e.g. Briss) to reframe them to be more suitable but that s laborious. The newer model, the Remarkable Paper Pro, might address both those issues: its bigger; has illumination and has also added colour which would be a nice to have. It s also a lot more expensive. I had considered selling on the tablet after I finished my PhD. My current plan, inspired to some extent by my former colleague Aleksey Shipil v, who makes great use of his, is to have a go at using it more often, to see if it continues to provide value for me: more noodling out thoughts for work tasks, more drawings (e.g. plans for 3D models) and more reading of tech books.

AI and Secure Messaging Don't Mix Over on the ACLU's Free Future blog, I just published an article titled AI and Secure Messaging Don't Mix. The blogpost assumes for the sake of the argument that people might actually want to have an AI involved in their personal conversations, and explores why Meta's Private Processing doesn't offer the level of assurance that they want it to offer. In short, the promises of "confidential cloud computing" are built on shaky foundations, especially against adversaries as powerful as Meta themselves. If you really want AI in your chat, the baseline step for privacy preservation is to include it in your local compute base, not to use a network service! But these operators clearly don't value private communication as much as they value binding you to their services. But let's imagine some secure messenger that actually does put message confidentiality first -- and imagine they had integrated some sort of AI capability into the messenger. That at least bypasses the privacy questions around AI use. Would you really want to talk with your friends, as augmented by their local AI, though? Would you want an AI, even one running locally with perfect privacy, intervening in your social connections? What if it summarized your friend's messages to you in a way that led you to misunderstand (or ignore) an important point your friend had made? What if it encouraged you to make an edgy joke that comes across wrong? Or to say something that seriously upsets a friend? How would you respond? How would you even know that it had happened? My handle is dkg. More times than i can count, i've had someone address me in a chat as "dog" and then cringe and apologize and blame their spellchecker/autocorrect. I can laugh these off because the failure mode is so obvious and transparent -- and repeatable. (also, dogs are awesome, so i don't really mind!) But when our attention (and our responses!) are being shaped and molded by these plausibility engines, how will we even know that mistakes are being made? What if the plausibility engine you've hooked into your messenger embeds subtle (or unsubtle!) bias? Don't we owe it to each other to engage with actual human attention?

## 0.23	2025-12-20
commit be15aa25dea40aea66a8534143fb81b29d2e6c08
Author: C.J. Collier 
Date:   Sat Dec 20 22:40:44 2025 +0000
    Fixes C-level test infrastructure and adds more test cases for upb_to_sv conversions.
    
    - **Makefile.PL:**
        - Allow  extra_src  in  c_test_config.json  to be an array.
        - Add ASan flags to CCFLAGS and LDDLFLAGS for better debugging.
        - Corrected echo newlines in  test_c  target.
    - **c_test_config.json:**
        - Added missing type test files to  deps  and  extra_src  for  convert/sv_to_upb  and  convert/upb_to_sv  test runners.
    - **t/c/convert/upb_to_sv.c:**
        - Fixed a double free of  test_pool .
        - Added missing includes for type test headers.
        - Updated test plan counts.
    - **t/c/convert/sv_to_upb.c:**
        - Added missing includes for type test headers.
        - Updated test plan counts.
        - Corrected Perl interpreter initialization.
    - **t/c/convert/types/**:
        - Added missing  test_util.h  include in new type test headers.
        - Completed the set of  upb_to_sv  test cases for all scalar types by adding optional and repeated tests for  sfixed32 ,  sfixed64 ,  sint32 , and  sint64 , and adding repeated tests to the remaining scalar type files.
    - **Documentation:**
        - Updated  01-xs-testing.md  with more debugging tips, including ASan usage and checking for double frees and typos.
        - Updated  xs_learnings.md  with details from the recent segfault.
        - Updated  llm-plan-execution-instructions.md  to emphasize debugging steps.
## 0.22	2025-12-19
commit 2c171d9a5027e0150eae629729c9104e7f6b9d2b
Author: C.J. Collier 
Date:   Fri Dec 19 23:41:02 2025 +0000
    feat(perl,testing): Initialize C test framework and build system
    
    This commit sets up the foundation for the C-level tests and the build system for the Perl Protobuf module:
    
    1.  **Makefile.PL Enhancements:**
        *   Integrates  Devel::PPPort  to generate  ppport.h  for better portability.
        *   Object files now retain their path structure (e.g.,  xs/convert/sv_to_upb.o ) instead of being flattened, improving build clarity.
        *   The  MY::postamble  is significantly revamped to dynamically generate build rules for all C tests located in  t/c/  based on the  t/c/c_test_config.json  file.
        *   C tests are linked against  libprotobuf_common.a  and use  ExtUtils::Embed  flags.
        *   Added  JSON::MaybeXS  to  PREREQ_PM .
        *   The  test  target now also depends on the  test_c  target.
    
    2.  **C Test Infrastructure ( t/c/ ):
        *   Introduced  t/c/c_test_config.json  to configure individual C test builds, specifying dependencies and extra source files.
        *   Created  t/c/convert/test_util.c  and  .h  for shared test functions like loading descriptors.
        *   Initial  t/c/convert/upb_to_sv.c  and  t/c/convert/sv_to_upb.c  test runners.
        *   Basic  t/c/integration/030_protobuf_coro.c  for Coro safety testing on core utils using  libcoro .
        *   Basic  t/c/integration/035_croak_test.c  for testing exception handling.
        *   Basic  t/c/integration/050_convert.c  for integration testing conversions.
    
    3.  **Test Proto:** Updated  t/data/test.proto  with more field types for conversion testing and regenerated  test_descriptor.bin .
    
    4.  **XS Test Harness ( t/c/upb-perl-test.h ):** Added  like_n  macro for length-aware regex matching.
    
    5.  **Documentation:** Updated architecture and plan documents to reflect the C test structure.
    6.  **ERRSV Testing:** Note that the C tests ( t/c/ ) will primarily check *if* a  croak  occurs (i.e., that the exception path is taken), but will not assert on the string content of  ERRSV . Reliably testing  $@  content requires the full Perl test environment with  Test::More , which will be done in the  .t  files when testing the Perl API.
    
    This provides a solid base for developing and testing the XS and C components of the module.
## 0.21	2025-12-18
commit a8b6b6100b2cf29c6df1358adddb291537d979bc
Author: C.J. Collier 
Date:   Thu Dec 18 04:20:47 2025 +0000
    test(C): Add integration tests for Milestone 2 components
    
    - Created t/c/integration/030_protobuf.c to test interactions
      between obj_cache, arena, and utils.
    - Added this test to t/c/c_test_config.json.
    - Verified that all C tests for Milestones 2 and 3 pass,
      including the libcoro-based stress test.
## 0.20	2025-12-18
commit 0fcad68680b1f700a83972a7c1c48bf3a6958695
Author: C.J. Collier 
Date:   Thu Dec 18 04:14:04 2025 +0000
    docs(plan): Add guideline review reminders to milestones
    
    - Added a "[ ] REFRESH: Review all documents in @perl/doc/guidelines/**"
      checklist item to the start of each component implementation
      milestone (C and Perl layers).
    - This excludes Integration Test milestones.
## 0.19	2025-12-18
commit 987126c4b09fcdf06967a98fa3adb63d7de59a34
Author: C.J. Collier 
Date:   Thu Dec 18 04:05:53 2025 +0000
    docs(plan): Add C-level and Perl-level Coro tests to milestones
    
    - Added checklist items for  libcoro -based C tests
      (e.g.,  t/c/integration/050_convert_coro.c ) to all C layer
      integration milestones (050 through 220).
    - Updated  030_Integration_Protobuf.md  to standardise checklist
      items for the existing  030_protobuf_coro.c  test.
    - Removed the single  xt/author/coro-safe.t  item from
       010_Build.md .
    - Added checklist items for Perl-level  Coro  tests
      (e.g.,  xt/coro/240_arena.t ) to each Perl layer
      integration milestone (240 through 400).
    - Created  perl/t/c/c_test_config.json  to manage C test
      configurations externally.
    - Updated  perl/doc/architecture/testing/01-xs-testing.md  to describe
      both C-level  libcoro  and Perl-level  Coro  testing strategies.
## 0.18	2025-12-18
commit 6095a5a610401a6035a81429d0ccb9884d53687b
Author: C.J. Collier 
Date:   Thu Dec 18 02:34:31 2025 +0000
    added coro testing to c layer milestones
## 0.17	2025-12-18
commit cc0aae78b1f7f675fc8a1e99aa876c0764ea1cce
Author: C.J. Collier 
Date:   Thu Dec 18 02:26:59 2025 +0000
    docs(plan): Refine test coverage checklist items for SMARTness
    
    - Updated the "Tests provide full coverage" checklist items in
      C layer plan files (020, 040, 060, 080, 100, 120, 140, 160, 180, 200)
      to explicitly mention testing all public functions in the
      corresponding header files.
    - Expanded placeholder checklists in 140, 160, 180, 200.
    - Updated the "Tests provide full coverage" and "Add coverage checks"
      checklist items in Perl layer plan files (230, 250, 270, 290, 310, 330,
      350, 370, 390) to be more specific about the scope of testing
      and the use of  Test::TestCoverage .
    - Expanded Well-Known Types milestone (350) to detail each type.
## 0.16	2025-12-18
commit e4b601f14e3817a17b0f4a38698d981dd4cb2818
Author: C.J. Collier 
Date:   Thu Dec 18 02:07:35 2025 +0000
    docs(plan): Full refactoring of C and Perl plan files
    
    - Split both ProtobufPlan-C.md and ProtobufPlan-Perl.md into
      per-milestone files under the  perl/doc/plan/  directory.
    - Introduced Integration Test milestones after each component
      milestone in both C and Perl plans.
    - Numbered milestone files sequentially (e.g., 010_Build.md,
      230_Perl_Arena.md).
    - Updated main ProtobufPlan-C.md and ProtobufPlan-Perl.md to
      act as Tables of Contents.
    - Ensured consistent naming for integration test files
      (e.g.,  t/c/integration/030_protobuf.c ,  t/integration/260_descriptor_pool.t ).
    - Added architecture review steps to the end of all milestones.
    - Moved Coro safety test to C layer Milestone 1.
    - Updated Makefile.PL to support new test structure and added Coro.
    - Moved and split t/c/convert.c into t/c/convert/*.c.
    - Moved other t/c/*.c tests into t/c/protobuf/*.c.
    - Deleted old t/c/convert.c.
## 0.15	2025-12-17
commit 649cbacf03abb5e7293e3038bb451c0406e9d0ce
Author: C.J. Collier 
Date:   Wed Dec 17 23:51:22 2025 +0000
    docs(plan): Refactor and reset ProtobufPlan.md
    
    - Split the plan into ProtobufPlan-C.md and ProtobufPlan-Perl.md.
    - Reorganized milestones to clearly separate C layer and Perl layer development.
    - Added more granular checkboxes for each component:
      - C Layer: Create test, Test coverage, Implement, Tests pass.
      - Perl Layer: Create test, Test coverage, Implement Module/XS, Tests pass, C-Layer adjustments.
    - Reset all checkboxes to  [ ]  to prepare for a full audit.
    - Updated status in architecture/api and architecture/core documents to "Not Started".
    
    feat(obj_cache): Add unregister function and enhance tests
    
    - Added  protobuf_unregister_object  to  xs/protobuf/obj_cache.c .
    - Updated  xs/protobuf/obj_cache.h  with the new function declaration.
    - Expanded tests in  t/c/protobuf_obj_cache.c  to cover unregistering,
      overwriting keys, and unregistering non-existent keys.
    - Corrected the test plan count in  t/c/protobuf_obj_cache.c  to 17.
## 0.14	2025-12-17
commit 40b6ad14ca32cf16958d490bb575962f88d868a1
Author: C.J. Collier 
Date:   Wed Dec 17 23:18:27 2025 +0000
    feat(arena): Complete C layer for Arena wrapper
    
    This commit finalizes the C-level implementation for the Protobuf::Arena wrapper.
    
    - Adds  PerlUpb_Arena_Destroy  for proper cleanup from Perl's DEMOLISH.
    - Enhances error checking in  PerlUpb_Arena_Get .
    - Expands C-level tests in  t/c/protobuf_arena.c  to cover memory allocation
      on the arena and lifecycle through  PerlUpb_Arena_Destroy .
    - Corrects embedded Perl initialization in the C test.
    
    docs(plan): Refactor ProtobufPlan.md
    
    - Restructures the development plan to clearly separate "C Layer" and
      "Perl Layer" tasks within each milestone.
    - This aligns the plan with the "C-First Implementation Strategy" and improves progress tracking.
## 0.13	2025-12-17
commit c1e566c25f62d0ae9f195a6df43b895682652c71
Author: C.J. Collier 
Date:   Wed Dec 17 22:00:40 2025 +0000
    refactor(perl): Rename C tests and enhance Makefile.PL
    
    - Renamed test files in  t/c/  to better match the  xs  module structure:
        -  01-cache.c  ->  protobuf_obj_cache.c 
        -  02-arena.c  ->  protobuf_arena.c 
        -  03-utils.c  ->  protobuf_utils.c 
        -  04-convert.c  ->  convert.c 
        -  load_test.c  ->  upb_descriptor_load.c 
    - Updated  perl/Makefile.PL  to reflect the new test names in  MY::postamble 's  $c_test_config .
    - Refactored the  $c_test_config  generation in  Makefile.PL  to reduce repetition by using a default flags hash and common dependencies array.
    - Added a  fail()  macro to  perl/t/c/upb-perl-test.h  for consistency.
    - Modified  t/c/upb_descriptor_load.c  to use the  t/c/upb-perl-test.h  macros, making its output consistent with other C tests.
    - Added a skeleton for  t/c/convert.c  to test the conversion functions.
    - Updated documentation in  ProtobufPlan.md  and  architecture/testing/01-xs-testing.md  to reflect new test names.
## 0.12	2025-12-17
commit d8cb5dd415c6c129e71cd452f78e29de398a82c9
Author: C.J. Collier 
Date:   Wed Dec 17 20:47:38 2025 +0000
    feat(perl): Refactor XS code into subdirectories
    
    This commit reorganizes the C code in the  perl/xs/  directory into subdirectories, mirroring the structure of the Python UPB extension. This enhances modularity and maintainability.
    
    - Created subdirectories for each major component:  convert ,  descriptor ,  descriptor_containers ,  descriptor_pool ,  extension_dict ,  map ,  message ,  protobuf ,  repeated , and  unknown_fields .
    - Created skeleton  .h  and  .c  files within each subdirectory to house the component-specific logic.
    - Updated top-level component headers (e.g.,  perl/xs/descriptor.h ) to include the new sub-headers.
    - Updated top-level component source files (e.g.,  perl/xs/descriptor.c ) to include their main header and added stub initialization functions (e.g.,  PerlUpb_InitDescriptor ).
    - Moved code from the original  perl/xs/protobuf.c  to new files in  perl/xs/protobuf/  (arena, obj_cache, utils).
    - Moved code from the original  perl/xs/convert.c  to new files in  perl/xs/convert/  (upb_to_sv, sv_to_upb).
    - Updated  perl/Makefile.PL  to use a glob ( xs/*/*.c ) to find the new C source files in the subdirectories.
    - Added  perl/doc/architecture/core/07-xs-file-organization.md  to document the new structure.
    - Updated  perl/doc/ProtobufPlan.md  and other architecture documents to reference the new organization.
    - Corrected self-referential includes in the newly created .c files.
    
    This restructuring provides a solid foundation for further development and makes it easier to port logic from the Python implementation.
## 0.11	2025-12-17
commit cdedcd13ded4511b0464f5d3bdd72ce6d34e73fc
Author: C.J. Collier 
Date:   Wed Dec 17 19:57:52 2025 +0000
    feat(perl): Implement C-first testing and core XS infrastructure
    
    This commit introduces a significant refactoring of the Perl XS extension, adopting a C-first development approach to ensure a robust foundation.
    
    Key changes include:
    
    -   **C-Level Testing Framework:** Established a C-level testing system in  t/c/  with a dedicated Makefile, using an embedded Perl interpreter. Initial tests cover the object cache ( 01-cache.c ), arena wrapper ( 02-arena.c ), and utility functions ( 03-utils.c ).
    -   **Core XS Infrastructure:**
        -   Implemented a global object cache ( xs/protobuf.c ) to manage Perl wrappers for UPB objects, using weak references.
        -   Created an  upb_Arena  wrapper ( xs/protobuf.c ).
        -   Consolidated common XS helper functions into  xs/protobuf.h  and  xs/protobuf.c .
    -   **Makefile.PL Enhancements:** Updated to support building and linking C tests, incorporating flags from  ExtUtils::Embed , and handling both  .c  and  .cc  source files.
    -   **XS File Reorganization:** Restructured XS files to mirror the Python UPB extension's layout (e.g.,  message.c ,  descriptor.c ). Removed older, monolithic  .xs  files.
    -   **Typemap Expansion:** Added extensive typemap entries in  perl/typemap  to handle conversions between Perl objects and various  const upb_*Def*  pointers.
    -   **Descriptor Tests:** Added a new test suite  t/02-descriptor.t  to validate descriptor loading and accessor methods.
    -   **Documentation:** Updated development plans and guidelines ( ProtobufPlan.md ,  xs_learnings.md , etc.) to reflect the C-first strategy, new testing methods, and lessons learned.
    -   **Build Cleanup:** Removed  ppport.h  from  .gitignore  as it's no longer used, due to  -DPERL_NO_PPPORT  being set in  Makefile.PL .
    
    This C-first approach allows for more isolated and reliable testing of the core logic interacting with the UPB library before higher-level Perl APIs are built upon it.
## 0.10	2025-12-17
commit 1ef20ade24603573905cb0376670945f1ab5d829
Author: C.J. Collier 
Date:   Wed Dec 17 07:08:29 2025 +0000
    feat(perl): Implement C-level tests and core XS utils
    
    This commit introduces a C-level testing framework for the XS layer and implements key components:
    
    1.  **C-Level Tests ( t/c/ )**:
        *   Added  t/c/Makefile  to build standalone C tests.
        *   Created  t/c/upb-perl-test.h  with macros for TAP-compliant C tests ( plan ,  ok ,  is ,  is_string ,  diag ).
        *   Implemented  t/c/01-cache.c  to test the object cache.
        *   Implemented  t/c/02-arena.c  to test  Protobuf::Arena  wrappers.
        *   Implemented  t/c/03-utils.c  to test string utility functions.
        *   Corrected include paths and diagnostic messages in C tests.
    
    2.  **XS Object Cache ( xs/protobuf.c )**:
        *   Switched to using stringified pointers ( %p ) as hash keys for stability.
        *   Fixed a critical double-free bug in  PerlUpb_ObjCache_Delete  by removing an extra  SvREFCNT_dec  on the lookup key.
    
    3.  **XS Arena Wrapper ( xs/protobuf.c )**:
        *   Corrected  PerlUpb_Arena_New  to use  newSVrv  and  PTR2IV  for opaque object wrapping.
        *   Corrected  PerlUpb_Arena_Get  to safely unwrap the arena pointer.
    
    4.  **Makefile.PL ( perl/Makefile.PL )**:
        *   Added  -Ixs  to  INC  to allow C tests to find  t/c/upb-perl-test.h  and  xs/protobuf.h .
        *   Added  LIBS  to link  libprotobuf_common.a  into the main  Protobuf.so .
        *   Added C test targets  01-cache ,  02-arena ,  03-utils  to the test config in  MY::postamble .
    
    5.  **Protobuf.pm ( perl/lib/Protobuf.pm )**:
        *   Added  use XSLoader;  to load the compiled XS code.
    
    6.  **New files  xs/util.h **:
        *   Added initial type conversion function.
    
    These changes establish a foundation for testing the C-level interface with UPB and fix crucial bugs in the object cache implementation.
## 0.09	2025-12-17
commit 07d61652b032b32790ca2d3848243f9d75ea98f4
Author: C.J. Collier 
Date:   Wed Dec 17 04:53:34 2025 +0000
    feat(perl): Build system and C cache test for Perl XS
    
    This commit introduces the foundational pieces for the Perl XS implementation, focusing on the build system and a C-level test for the object cache.
    
    -   **Makefile.PL:**
        -   Refactored C test compilation rules in  MY::postamble  to use a hash ( $c_test_config ) for better organization and test-specific flags.
        -   Integrated  ExtUtils::Embed  to provide necessary compiler and linker flags for embedding the Perl interpreter, specifically for the  t/c/01-cache.c  test.
        -   Correctly constructs the path to the versioned Perl library ( libperl.so.X.Y.Z ) using  $Config archlib  and  $Config libperl  to ensure portability.
        -   Removed  VERSION_FROM  and  ABSTRACT_FROM  to avoid dependency on  .pm  files for now.
    
    -   **C Cache Test (t/c/01-cache.c):**
        -   Added a C test to exercise the object cache functions implemented in  xs/protobuf.c .
        -   Includes tests for adding, getting, deleting, and weak reference behavior.
    
    -   **XS Cache Implementation (xs/protobuf.c, xs/protobuf.h):**
        -   Implemented  PerlUpb_ObjCache_Init ,  PerlUpb_ObjCache_Add ,  PerlUpb_ObjCache_Get ,  PerlUpb_ObjCache_Delete , and  PerlUpb_ObjCache_Destroy .
        -   Uses a Perl hash ( HV* ) for the cache.
        -   Keys are string representations of the C pointers, created using  snprintf  with  "%llx" .
        -   Values are weak references ( sv_rvweaken ) to the Perl objects ( SV* ).
        -    PerlUpb_ObjCache_Get  now correctly returns an incremented reference to the original SV, not a copy.
        -    PerlUpb_ObjCache_Destroy  now clears the hash before decrementing its refcount.
    
    -   **t/c/upb-perl-test.h:**
        -   Updated  is_sv  to perform direct pointer comparison ( got == expected ).
    
    -   **Minor:** Added  util.h  (currently empty), updated  typemap .
    
    These changes establish a working C-level test environment for the XS components.
## 0.08	2025-12-17
commit d131fd22ea3ed8158acb9b0b1fe6efd856dc380e
Author: C.J. Collier 
Date:   Wed Dec 17 02:57:48 2025 +0000
    feat(perl): Update docs and core XS files
    
    - Explicitly add TDD cycle to ProtobufPlan.md.
    - Clarify mirroring of Python implementation in upb-interfacing.md for both C and Perl layers.
    - Branch and adapt python/protobuf.h and python/protobuf.c to perl/xs/protobuf.h and perl/xs/protobuf.c, including the object cache implementation. Removed old cache.* files.
    - Create initial C test for the object cache in t/c/01-cache.c.
## 0.07	2025-12-17
commit 56fd6862732c423736a2f9a9fb1a2816fc59e9b0
Author: C.J. Collier 
Date:   Wed Dec 17 01:09:18 2025 +0000
    feat(perl): Align Perl UPB architecture docs with Python
    
    Updates the Perl Protobuf architecture documents to more closely align with the design and implementation strategies used in the Python UPB extension.
    
    Key changes:
    
    -   **Object Caching:** Mandates a global, per-interpreter cache using weak references for all UPB-derived objects, mirroring Python's  PyUpb_ObjCache .
    -   **Descriptor Containers:** Introduces a new document outlining the plan to use generic XS container types (Sequence, ByNameMap, ByNumberMap) with vtables to handle collections of descriptors, similar to Python's  descriptor_containers.c .
    -   **Testing:** Adds a note to the testing strategy to port relevant test cases from the Python implementation to ensure feature parity.
## 0.06	2025-12-17
commit 6009ce6ab64eccce5c48729128e5adf3ef98e9ae
Author: C.J. Collier 
Date:   Wed Dec 17 00:28:20 2025 +0000
    feat(perl): Implement object caching and fix build
    
    This commit introduces several key improvements to the Perl XS build system and core functionality:
    
    1.  **Object Caching:**
        *   Introduces  xs/protobuf.c  and  xs/protobuf.h  to implement a caching mechanism ( protobuf_c_to_perl_obj ) for wrapping UPB C pointers into Perl objects. This uses a hash and weak references to ensure object identity and prevent memory leaks.
        *   Updates the  typemap  to use  protobuf_c_to_perl_obj  for  upb_MessageDef *  output, ensuring descriptor objects are cached.
        *   Corrected  sv_weaken  to the correct  sv_rvweaken  function.
    
    2.  **Makefile.PL Enhancements:**
        *   Switched to using the Bazel-generated UPB descriptor sources from  bazel-bin/src/google/protobuf/_virtual_imports/descriptor_proto/google/protobuf/ .
        *   Updated  INC  paths to correctly locate the generated headers.
        *   Refactored  MY::dynamic_lib  to ensure the static library  libprotobuf_common.a  is correctly linked into each generated  .so  module, resolving undefined symbol errors.
        *   Overrode  MY::test  to use  prove -b -j$(nproc) t/*.t xt/*.t  for running tests.
        *   Cleaned up  LIBS  and  LDDLFLAGS  usage.
    
    3.  **Documentation:**
        *   Updated  ProtobufPlan.md  to reflect the current status and design decisions.
        *   Reorganized architecture documents into subdirectories.
        *   Added  object-caching.md  and  c-perl-interface.md .
        *   Updated  llm-guidance.md  with notes on  upb/upb.h  and  sv_rvweaken .
    
    4.  **Testing:**
        *   Fixed  xt/03-moo_immutable.t  to skip tests if no Moo modules are found.
    
    This resolves the build issues and makes the core test suite pass.
## 0.05	2025-12-16
commit 177d2f3b2608b9d9c415994e076a77d8560423b8
Author: C.J. Collier 
Date:   Tue Dec 16 19:51:36 2025 +0000
    Refactor: Rename namespace to Protobuf, build system and doc updates
    
    This commit refactors the primary namespace from  ProtoBuf  to  Protobuf 
    to align with the style guide. This involves renaming files, directories,
    and updating package names within all Perl and XS files.
    
    **Namespace Changes:**
    
    *   Renamed  perl/lib/ProtoBuf  to  perl/lib/Protobuf .
    *   Moved and updated  ProtoBuf.pm  to  Protobuf.pm .
    *   Moved and updated  ProtoBuf::Descriptor  to  Protobuf::Descriptor  (.pm & .xs).
    *   Removed other  ProtoBuf::*  stubs (Arena, DescriptorPool, Message).
    *   Updated  MODULE  and  PACKAGE  in  Descriptor.xs .
    *   Updated  NAME ,  *_FROM  in  perl/Makefile.PL .
    *   Replaced  ProtoBuf  with  Protobuf  throughout  perl/typemap .
    *   Updated namespaces in test files  t/01-load-protobuf-descriptor.t  and  t/02-descriptor.t .
    *   Updated namespaces in all documentation files under  perl/doc/ .
    *   Updated paths in  perl/.gitignore .
    
    **Build System Enhancements (Makefile.PL):**
    
    *   Included  xs/*.c  files in the common object files list.
    *   Added  -I.  to the  INC  paths.
    *   Switched from  MYEXTLIB  to  LIBS => ['-L$(CURDIR) -lprotobuf_common']  for linking.
    *   Removed custom keys passed to  WriteMakefile  for postamble.
    *    MY::postamble  now sources variables directly from the main script scope.
    *   Added  all :: $ common_lib  dependency in  MY::postamble .
    *   Added  t/c/load_test.c  compilation rule in  MY::postamble .
    *   Updated  clean  target to include  blib .
    *   Added more modules to  TEST_REQUIRES .
    *   Removed the explicit  PM  and  XS  keys from  WriteMakefile , relying on  XSMULTI => 1 .
    
    **New Files:**
    
    *    perl/lib/Protobuf.pm 
    *    perl/lib/Protobuf/Descriptor.pm 
    *    perl/lib/Protobuf/Descriptor.xs 
    *    perl/t/01-load-protobuf-descriptor.t 
    *    perl/t/02-descriptor.t 
    *    perl/t/c/load_test.c : Standalone C test for UPB.
    *    perl/xs/types.c  &  perl/xs/types.h : For Perl/C type conversions.
    *    perl/doc/architecture/upb-interfacing.md 
    *    perl/xt/03-moo_immutable.t : Test for Moo immutability.
    
    **Deletions:**
    
    *   Old test files:  t/00_load.t ,  t/01_basic.t ,  t/02_serialize.t ,  t/03_message.t ,  t/04_descriptor_pool.t ,  t/05_arena.t ,  t/05_message.t .
    *   Removed  lib/ProtoBuf.xs  as it's not needed with  XSMULTI .
    
    **Other:**
    
    *   Updated  test_descriptor.bin  (binary change).
    *   Significant content updates to markdown documentation files in  perl/doc/architecture  and  perl/doc/internal  reflecting the new architecture and learnings.
## 0.04	2025-12-14
commit 92de5d482c8deb9af228f4b5ce31715d3664d6ee
Author: C.J. Collier 
Date:   Sun Dec 14 21:28:19 2025 +0000
    feat(perl): Implement Message object creation and fix lifecycles
    
    This commit introduces the basic structure for  ProtoBuf::Message  object
    creation, linking it with  ProtoBuf::Descriptor  and  ProtoBuf::DescriptorPool ,
    and crucially resolves a SEGV by fixing object lifecycle management.
    
    Key Changes:
    
    1.  ** ProtoBuf::Descriptor :** Added  _pool  attribute to hold a strong
        reference to the parent  ProtoBuf::DescriptorPool . This is essential to
        prevent the pool and its C  upb_DefPool  from being garbage collected
        while a descriptor is still in use.
    
    2.  ** ProtoBuf::DescriptorPool :**
        *    find_message_by_name : Now passes the  $self  (the pool object) to the
             ProtoBuf::Descriptor  constructor to establish the lifecycle link.
        *   XSUB  pb_dp_find_message_by_name : Updated to accept the pool  SV*  and
            store it in the descriptor's  _pool  attribute.
        *   XSUB  _load_serialized_descriptor_set : Renamed to avoid clashing with the
            Perl method name. The Perl wrapper now correctly calls this internal XSUB.
        *    DEMOLISH : Made safer by checking for attribute existence.
    
    3.  ** ProtoBuf::Message :**
        *   Implemented using Moo with lazy builders for  _upb_arena  and
             _upb_message .
        *    _descriptor  is a required argument to  new() .
        *   XS functions added for creating the arena ( pb_msg_create_arena ) and
            the  upb_Message  ( pb_msg_create_upb_message ).
        *    pb_msg_create_upb_message  now extracts the  upb_MessageDef*  from the
            descriptor and uses  upb_MessageDef_MiniTable()  to get the minitable
            for  upb_Message_New() .
        *    DEMOLISH : Added to free the message's arena.
    
    4.  ** Makefile.PL :**
        *   Added  -g  to  CCFLAGS  for debugging symbols.
        *   Added Perl CORE include path to  MY::postamble 's  base_flags .
    
    5.  **Tests:**
        *    t/04_descriptor_pool.t : Updated to check the structure of the
            returned  ProtoBuf::Descriptor .
        *    t/05_message.t : Now uses a descriptor obtained from a real pool to
            test  ProtoBuf::Message->new() .
    
    6.  **Documentation:**
        *   Updated  ProtobufPlan.md  to reflect progress.
        *   Updated several files in  doc/architecture/  to match the current
            implementation details, especially regarding arena management and object
            lifecycles.
        *   Added  doc/internal/development_cycle.md  and  doc/internal/xs_learnings.md .
    
    With these changes, the SEGV is resolved, and message objects can be successfully
    created from descriptors.
## 0.03	2025-12-14
commit 6537ad23e93680c2385e1b571d84ed8dbe2f68e8
Author: C.J. Collier 
Date:   Sun Dec 14 20:23:41 2025 +0000
    Refactor(perl): Object-Oriented DescriptorPool with Moo
    
    This commit refactors the  ProtoBuf::DescriptorPool  to be fully object-oriented using Moo, and resolves several issues related to XS, typemaps, and test data.
    
    Key Changes:
    
    1.  **Moo Object:**  ProtoBuf::DescriptorPool.pm  now uses  Moo  to define the class. The  upb_DefPool  pointer is stored as a lazy attribute  _upb_defpool .
    2.  **XS Lifecycle:**  DescriptorPool.xs  now has  pb_dp_create_pool  called by the Moo builder and  pb_dp_free_pool  called from  DEMOLISH  to manage the  upb_DefPool  lifecycle per object.
    3.  **Typemap:** The  perl/typemap  file has been significantly updated to handle the conversion between the  ProtoBuf::DescriptorPool  Perl object and the  upb_DefPool *  C pointer. This includes:
        *   Mapping  upb_DefPool *  to  T_PTR .
        *   An  INPUT  section for  ProtoBuf::DescriptorPool  to extract the pointer from the object's hash, triggering the lazy builder if needed via  call_method .
        *   An  OUTPUT  section for  upb_DefPool *  to convert the pointer back to a Perl integer, used by the builder.
    4.  **Method Renaming:**  add_file_descriptor_set_binary  is now  load_serialized_descriptor_set .
    5.  **Test Data:**
        *   Added  perl/t/data/test.proto  with a sample message and enum.
        *   Generated  perl/t/data/test_descriptor.bin  using  protoc .
        *   Removed  t/data/  from  .gitignore  to ensure test data is versioned.
    6.  **Test Update:**  t/04_descriptor_pool.t  is updated to use the new OO interface, load the generated descriptor set, and check for message definitions.
    7.  **Build Fixes:**
        *   Corrected  #include  paths in  DescriptorPool.xs  to be relative to the  upb/  directory (e.g.,  upb/wire/decode.h ).
        *   Added  -I../upb  to  CCFLAGS  in  Makefile.PL .
        *   Reordered  INC  paths in  Makefile.PL  to prioritize local headers.
    
    **Note:** While tests now pass in some environments, a SEGV issue persists in  make test  runs, indicating a potential memory or lifecycle issue within the XS layer that needs further investigation.
## 0.02	2025-12-14
commit 6c9a6f1a5f774dae176beff02219f504ea3a6e07
Author: C.J. Collier 
Date:   Sun Dec 14 20:13:09 2025 +0000
    Fix(perl): Correct UPB build integration and generated file handling
    
    This commit resolves several issues to achieve a successful build of the Perl extension:
    
    1.  **Use Bazel Generated Files:** Switched from compiling UPB's stage0 descriptor.upb.c to using the Bazel-generated  descriptor.upb.c  and  descriptor.upb_minitable.c  located in  bazel-bin/src/google/protobuf/_virtual_imports/descriptor_proto/google/protobuf/ .
    2.  **Updated Include Paths:** Added the  bazel-bin  path to  INC  in  WriteMakefile  and to  base_flags  in  MY::postamble  to ensure the generated headers are found during both XS and static library compilation.
    3.  **Removed Stage0:** Removed references to  UPB_STAGE0_DIR  and no longer include headers or source files from  upb/reflection/stage0/ .
    4.  **-fPIC:** Explicitly added  -fPIC  to  CCFLAGS  in  WriteMakefile  and ensured  $(CCFLAGS)  is used in the custom compilation rules in  MY::postamble . This guarantees all object files in the static library are compiled with position-independent code, resolving linker errors when creating the shared objects for the XS modules.
    5.  **Refined UPB Sources:** Used  File::Find  to recursively find UPB C sources, excluding  /conformance/  and  /reflection/stage0/  to avoid conflicts and unnecessary compilations.
    6.  **Arena Constructor:** Modified  ProtoBuf::Arena::pb_arena_new  XSUB to accept the class name argument passed from Perl, making it a proper constructor.
    7.  **.gitignore:** Added patterns to  perl/.gitignore  to ignore generated C files from XS ( lib/*.c ,  lib/ProtoBuf/*.c ), the copied  src_google_protobuf_descriptor.pb.cc , and the  t/data  directory.
    8.  **Build Documentation:** Updated  perl/doc/architecture/upb-build-integration.md  to reflect the new build process, including the Bazel prerequisite, include paths,  -fPIC  usage, and  File::Find .
    
    Build Steps:
    1.   bazel build //src/google/protobuf:descriptor_upb_proto  (from repo root)
    2.   cd perl 
    3.   perl Makefile.PL 
    4.   make 
    5.   make test  (Currently has expected failures due to missing test data implementation).
## 0.01	2025-12-14
commit 3e237e8a26442558c94075766e0d4456daaeb71d
Author: C.J. Collier 
Date:   Sun Dec 14 19:34:28 2025 +0000
    feat(perl): Initialize Perl extension scaffold and build system
    
    This commit introduces the  perl/  directory, laying the groundwork for the Perl Protocol Buffers extension. It includes the essential build files, linters, formatter configurations, and a vendored Devel::PPPort for XS portability.
    
    Key components added:
    
    *   ** Makefile.PL **: The core  ExtUtils::MakeMaker  build script. It's configured to:
        *   Build a static library ( libprotobuf_common.a ) from UPB, UTF8_Range, and generated protobuf C/C++ sources.
        *   Utilize  XSMULTI => 1  to create separate shared objects for  ProtoBuf ,  ProtoBuf::Arena , and  ProtoBuf::DescriptorPool .
        *   Link each XS module against the common static library.
        *   Define custom compilation rules in  MY::postamble  to handle C vs. C++ flags and build the static library.
        *   Set up include paths for the project root, UPB, and other dependencies.
    
    *   **XS Stubs ( .xs  files)**:
        *    lib/ProtoBuf.xs : Placeholder for the main module's XS functions.
        *    lib/ProtoBuf/Arena.xs : XS interface for  upb_Arena  management.
        *    lib/ProtoBuf/DescriptorPool.xs : XS interface for  upb_DefPool  management.
    
    *   **Perl Module Stubs ( .pm  files)**:
        *    lib/ProtoBuf.pm : Main module, loads XS.
        *    lib/ProtoBuf/Arena.pm : Perl class for Arenas.
        *    lib/ProtoBuf/DescriptorPool.pm : Perl class for Descriptor Pools.
        *    lib/ProtoBuf/Message.pm : Base class for messages (TBD).
    
    *   **Configuration Files**:
        *    .gitignore : Ignores build artifacts, editor files, etc.
        *    .perlcriticrc : Configures Perl::Critic for static analysis.
        *    .perltidyrc : Configures perltidy for code formatting.
    
    *   ** Devel::PPPort **: Vendored version 3.72 to generate  ppport.h  for XS compatibility across different Perl versions.
    
    *   ** typemap **: Custom typemap for XS argument/result conversion.
    
    *   **Documentation ( doc/ )**: Initial architecture and plan documents.
    
    This provides a solid foundation for developing the UPB-based Perl extension.

tl;dr: There is a Debian git transition plan. It s going OK so far but we need help, especially with outreach and updating Debian s documentation.

• Goals of the Debian git transition project
  • Achievements so far, and current status
• Core engineering principle
  • Correspondence between dsc and git
  • Patches-applied vs patches-unapplied
  • Consequences, some of which are annoying
• Distributing the source code as git
  • Tracking the relevant git data, when changes are made in the legacy Archive
  • Why *.dgit.debian.org is not Salsa
• Roadmap
  • In progress
  • Future Technology
• Mindshare and adoption - please help!
  • A rant about publishing the source code
  • Documentation
• Personnel
  • Thanks

Goals of the Debian git transition project

0. Everyone who interacts with Debian source code should be able to do so entirely in git.

That means, more specifically:

1. All examination and edits to the source should be performed via normal git operations.
2. Source code should be transferred and exchanged as git data, not tarballs. git should be the canonical form everywhere.
3. Upstream git histories should be re-published, traceably, as part of formal git releases published by Debian.
4. No-one should have to learn about Debian Source Packages, which are bizarre, and have been obsoleted by modern version control.

This is very ambitious, but we have come a long way! Achievements so far, and current status We have come a very long way. But, there is still much to do - especially, the git transition team needs your help with adoption, developer outreach, and developer documentation overhaul. We ve made big strides towards goals 1 and 4. Goal 2 is partially achieved: we currently have dual running. Goal 3 is within our reach but depends on widespread adoption of tag2upload (and/or dgit push). Downstreams and users can obtain the source code of any Debian package in git form. (dgit clone, 2013). They can then work with this source code completely in git, including building binaries, merging new versions, even automatically (eg Raspbian, 2016), and all without having to deal with source packages at all (eg Wikimedia 2025). A Debian maintainer can maintain their own package entirely in git. They can obtain upstream source code from git, and do their packaging work in git (git-buildpackage, 2006). Every Debian maintainer can (and should!) release their package from git reliably and in a standard form (dgit push, 2013; tag2upload, 2025). This is not only more principled, but also more convenient, and with better UX, than pre-dgit tooling like dput. Indeed a Debian maintainer can now often release their changes to Debian, from git, using only git branches (so no tarballs). Releasing to Debian can be simply pushing a signed tag (tag2upload, 2025). A Debian maintainer can maintain a stack of changes to upstream source code in git (gbp pq 2009). They can even maintain such a delta series as a rebasing git branch, directly buildable, and use normal git rebase style operations to edit their changes, (git-dpm, 2010; git-debrebase, 2018) An authorised Debian developer can do a modest update to any package in Debian, even one maintained by someone else, working entirely in git in a standard and convenient way (dgit, 2013). Debian contributors can share their work-in-progress on git forges and collaborate using merge requests, git based code review, and so on. (Alioth, 2003; Salsa, 2018.) Core engineering principle The Debian git transition project is based on one core engineering principle: Every Debian Source Package can be losslessly converted to and from git. In order to transition away from Debian Source Packages, we need to gateway between the old dsc approach, and the new git approach. This gateway obviously needs to be bidirectional: source packages uploaded with legacy tooling like dput need to be imported into a canonical git representation; and of course git branches prepared by developers need to be converted to source packages for the benefit of legacy downstream systems (such as the Debian Archive and apt source). This bidirectional gateway is implemented in src:dgit, and is allowing us to gradually replace dsc-based parts of the Debian system with git-based ones. Correspondence between dsc and git A faithful bidirectional gateway must define an invariant: The canonical git tree, corresponding to a .dsc, is the tree resulting from dpkg-source -x. This canonical form is sometimes called the dgit view . It s sometimes not the same as the maintainer s git branch, because many maintainers are still working with patches-unapplied git branches. More on this below. (For 3.0 (quilt) .dscs, the canonical git tree doesn t include the quilt .pc directory.) Patches-applied vs patches-unapplied The canonical git format is patches applied . That is: If Debian has modified the upstream source code, a normal git clone of the canonical branch gives the modified source tree, ready for reading and building. Many Debian maintainers keep their packages in a different git branch format, where the changes made by Debian, to the upstream source code, are in actual patch files in a debian/patches/ subdirectory. Patches-applied has a number of important advantages over patches-unapplied:

• It is familiar to, and doesn t trick, outsiders to Debian. Debian insiders radically underestimate how weird patches-unapplied is. Even expert software developers can get very confused or even accidentally build binaries without security patches!
• Making changes can be done with just normal git commands, eg git commit. Many Debian insiders working with patches-unapplied are still using quilt(1), a footgun-rich contraption for working with patch files!
• When developing, one can make changes to upstream code, and to Debian packaging, together, without ceremony. There is no need to switch back and forth between patch queue and packaging branches (as with gbp pq), no need to commit patch files, etc. One can always edit every file and commit it with git commit.

The downside is that, with the (bizarre) 3.0 (quilt) source format, the patch files files in debian/patches/ must somehow be kept up to date. Nowadays though, tools like git-debrebase and git-dpm (and dgit for NMUs) make it very easy to work with patches-applied git branches. git-debrebase can deal very ergonomically even with big patch stacks. (For smaller packages which usually have no patches, plain git merge with an upstream git branch, and a much simpler dsc format, sidesteps the problem entirely.) Prioritising Debian s users (and other outsiders) We want everyone to be able to share and modify the software that they interact with. That means we should make source code truly accessible, on the user s terms. Many of Debian s processes assume everyone is an insider. It s okay that there are Debian insiders and that people feel part of something that they worked hard to become involved with. But lack of perspective can lead to software which fails to uphold our values. Our source code practices in particular, our determination to share properly (and systematically) are a key part of what makes Debian worthwhile at all. Like Debian s installer, we want our source code to be useable by Debian outsiders. This is why we have chosen to privilege a git branch format which is more familiar to the world at large, even if it s less popular in Debian. Consequences, some of which are annoying The requirement that the conversion be bidirectional, lossless, and context-free can be inconvenient. For example, we cannot support .gitattributes which modify files during git checkin and checkout. .gitattributes cause the meaning of a git tree to depend on the context, in possibly arbitrary ways, so the conversion from git to source package wouldn t be stable. And, worse, some source packages might not to be representable in git at all. Another example: Maintainers often have existing git branches for their packages, generated with pre-dgit tooling which is less careful and less principled than ours. That can result in discrepancies between git and dsc, which need to be resolved before a proper git-based upload can succeed. That some maintainers use patches-unapplied, and some patches-unapplied, means that there has to be some kind of conversion to a standard git representation. Choosing the less-popular patches-applied format as the canonical form, means that many packages need their git representation converted. It also means that user- and outsider-facing branches from browse,git .dgit.d.o and dgit clone are not always compatible with maintainer branches on Salsa. User-contributed changes need cherry-picking rather than merging, or conversion back to the maintainer format. The good news is that dgit can automate much of this, and the manual parts are usually easy git operations. Distributing the source code as git Our source code management should be normal, modern, and based on git. That means the Debian Archive is obsolete and needs to be replaced with a set of git repositories. The replacement repository for source code formally released to Debian is *.dgit.debian.org. This contains all the git objects for every git-based upload since 2013, including the signed tag for each released package version. The plan is that it will contain a git view of every uploaded Debian package, by centrally importing all legacy uploads into git. Tracking the relevant git data, when changes are made in the legacy Archive Currently, many critical source code management tasks are done by changes to the legacy Debian Archive, which works entirely with dsc files (and the associated tarballs etc). The contents of the Archive are therefore still an important source of truth. But, the Archive s architecture means it cannot sensibly directly contain git data. To track changes made in the Archive, we added the Dgit: field to the .dsc of a git-based upload (2013). This declares which git commit this package was converted from. and where those git objects can be obtained. Thus, given a Debian Source Package from a git-based upload, it is possible for the new git tooling to obtain the equivalent git objects. If the user is going to work in git, there is no need for any tarballs to be downloaded: the git data could be obtained from the depository using the git protocol. The signed tags, available from the git depository, have standardised metdata which gives traceability back to the uploading Debian contributor. Why *.dgit.debian.org is not Salsa We need a git depository - a formal, reliable and permanent git repository of source code actually released to Debian. Git forges like Gitlab can be very convenient. But Gitlab is not sufficiently secure, and too full of bugs, to be the principal and only archive of all our source code. (The open core business model of the Gitlab corporation, and the constant-churn development approach, are critical underlying problems.) Our git depository lacks forge features like Merge Requests. But:

• It is dependable, both in terms of reliability and security.
• It is append-only: once something is pushed, it is permanently recorded.
• Its access control is precisely that of the Debian Archive.
• Its ref namespace is standardised and corresponds to Debian releases.
• Pushes are authorised by PGP signatures, not ssh keys, so traceable.

The dgit git depository outlasted Alioth and it may well outlast Salsa. We need both a good forge, and the *.dgit.debian.org formal git depository. Roadmap In progress Right now we are quite focused on tag2upload. We are working hard on eliminating the remaining issues that we feel need to be addressed before declaring the service out of beta. Future Technology Whole-archive dsc importer Currently, the git depository only has git data for git-based package updates (tag2upload and dgit push). Legacy dput-based uploads are not currently present there. This means that the git-based and legacy uploads must be resolved client-side, by dgit clone. We will want to start importing legacy uploads to git. Then downstreams and users will be able to get the source code for any package simply with git clone, even if the maintainer is using legacy upload tools like dput. Support for git-based uploads to security.debian.org Security patching is a task which would particularly benefit from better and more formal use of git. git-based approaches to applying and backporting security patches are much more convenient than messing about with actual patch files. Currently, one can use git to help prepare a security upload, but it often involves starting with a dsc import (which lacks the proper git history) or figuring out a package maintainer s unstandardised git usage conventions on Salsa. And it is not possible to properly perform the security release as git. Internal Debian consumers switch to getting source from git Buildds, QA work such as lintian checks, and so on, could be simpler if they don t need to deal with source packages. And since git is actually the canonical form, we want them to use it directly. Problems for the distant future For decades, Debian has been built around source packages. Replacing them is a long and complex process. Certainly source packages are going to continue to be supported for the foreseeable future. There are no doubt going to be unanticipated problems. There are also foreseeable issues: for example, perhaps there are packages that work very badly when represented in git. We think we can rise to these challenges as they come up. Mindshare and adoption - please help! We and our users are very pleased with our technology. It is convenient and highly dependable. dgit in particular is superb, even if we say so ourselves. As technologists, we have been very focused on building good software, but it seems we have fallen short in the marketing department. A rant about publishing the source code git is the preferred form for modification. Our upstreams are overwhelmingly using git. We are overwhelmingly using git. It is a scandal that for many packages, Debian does not properly, formally and officially publish the git history. Properly publishing the source code as git means publishing it in a way that means that anyone can automatically and reliably obtain and build the exact source code corresponding to the binaries. The test is: could you use that to build a derivative? Putting a package in git on Salsa is often a good idea, but it is not sufficient. No standard branch structure git on Salsa is enforced, nor should it be (so it can t be automatically and reliably obtained), the tree is not in a standard form (so it can t be automatically built), and is not necessarily identical to the source package. So Vcs-Git fields, and git from Salsa, will never be sufficient to make a derivative. Debian is not publishing the source code! The time has come for proper publication of source code by Debian to no longer be a minority sport. Every maintainer of a package whose upstream is using git (which is nearly all packages nowadays) should be basing their work on upstream git, and properly publishing that via tag2upload or dgit. And it s not even difficult! The modern git-based tooling provides a far superior upload experience. A common misunderstanding dgit push is not an alternative to gbp pq or quilt. Nor is tag2upload. These upload tools complement your existing git workflow. They replace and improve source package building/signing and the subsequent dput. If you are using one of the usual git layouts on salsa, and your package is in good shape, you can adopt tag2upload and/or dgit push right away. git-debrebase is distinct and does provides an alternative way to manage your git packaging, do your upstream rebases, etc. Documentation Debian s documentation all needs to be updated, including particularly instructions for packaging, to recommend use of git-first workflows. Debian should not be importing git-using upstreams release tarballs into git. (Debian outsiders who discover this practice are typically horrified.) We should use only upstream git, work only in git, and properly release (and publish) in git form. We, the git transition team, are experts in the technology, and can provide good suggestions. But we do not have the bandwidth to also engage in the massive campaigns of education and documentation updates that are necessary especially given that (as with any programme for change) many people will be sceptical or even hostile. So we would greatly appreciate help with writing and outreach. Personnel We consider ourselves the Debian git transition team. Currently we are:

• Ian Jackson. Author and maintainer of dgit and git-debrebase. Co-creator of tag2upload. Original author of dpkg-source, and inventor in 1996 of Debian Source Packages. Alumnus of the Debian Technical Committee.
• Sean Whitton. Co-creator of the tag2upload system; author and maintainer of git-debpush. Co-maintainer of dgit. Debian Policy co-Editor. Former Chair of the Debian Technical Committee.

We wear the following hats related to the git transition:

• Maintainers of src:dgit
• tag2upload Delegates; operators of the tag2upload service.
• service operators of the git depository *.dgit.debian.org.

You can contact us:

• By email: Ian Jackson ijackson@chiark.greenend.org.uk; Sean Whitton spwhitton@spwhitton.name; git-debpush@packages.d.o.
• By filing bugs in the Debian Bug System against src:dgit.
• On OFTC IRC, as Diziet and spwhitton.

We do most of our heavy-duty development on Salsa. Thanks Particular thanks are due to Joey Hess, who, in the now-famous design session in Vaumarcus in 2013, helped invent dgit. Since then we have had a lot of support: most recently political support to help get tag2upload deployed, but also, over the years, helpful bug reports and kind words from our users, as well as translations and code contributions. Many other people have contributed more generally to support for working with Debian source code in git. We particularly want to mention Guido G nther (git-buildpackage); and of course Alexander Wirt, Joerg Jaspert, Thomas Goirand and Antonio Terceiro (Salsa administrators); and before them the Alioth administrators.

comments

MiniDebConf Navi Mumbai 2025 which was MiniDebConf Mumbai, which in turn was FOSSMumbai x MiniDebian Conference, happened on 13th and 14th December, 2025, with a hotel as Day 1 venue and a college on Day 2. Originally planned for the 8th of November, it got postponed to December due to operational reasons. Most of the on-ground logistics and other heavy lifting was done by Arya, Vidhya, MumbaiFOSS, and the Remigies Technologies team, so we didn t had to worry much. This time, I gave a talk on Basics of a Free Software Mirror (and how Debian does it) (Presentation URL). I had the idea for this talk for a while and gave a KDE version of it during KDE India Conf 2025. The gist was to explain how Free Software is delivered to users and how one can help. For MDC, I focused a bit on Debian mirror network(s) and who else host mirrors in India and trends. At the onset someone mentioned my Termux mirror. Termux is a good project to get into mirror hosting with. I got into mirroring with it. It has low traffic (usually less than 20 GB/day) demands with a high request count and can be done on an existing 6 USD Digital Ocean nodes. Q&A time turned out more interesting than I anticipated. Folks touched upon commercial CDNs instead of community mirrors, supply chain security issues, and a bit of other stuff. We had quite a number of interesting talks and I remember when Arya was telling me during CFP time, bro we have too many talks now :D. Now, preparations have already started for MiniDebConf Kanpur 2026, scheduled for March 14th and 15th at the IIT campus. If you want to help, see the following thread. See you in the next one.

In January 2024 I wrote about the insanity of the Magnificent Seven dominating the MSCI World Index, and I wondered how long the number can continue to go up? It has continued to surge upward at an accelerating pace, which makes me worry that a crash is likely closer. As a software professional, I decided to analyze whether using stop-loss orders could reliably automate avoiding deep drawdowns. As everyone with some savings in the stock market (hopefully) knows, the stock market eventually experiences crashes. It is just a matter of when and how deep the crash will be. Staying on the sidelines for years is not a good investment strategy, as inflation will erode the value of your savings. Assuming the current true inflation rate is around 7%, a restaurant dinner that costs 20 euros today will cost 24.50 euros in three years. Savings of 1000 euros today would drop in purchasing power from 50 dinners to only 40 dinners in three years. Hence, if you intend to retain the value of your hard-earned savings, they need to be invested in something that grows in value. Most people try to beat inflation by buying shares in stable companies, directly or via broad market ETFs. These historically grow faster than inflation during normal years, but likely drop in value during recessions.

What is a trailing stop-loss order? What if you could buy stocks to benefit from their value increasing without having to worry about a potential crash? All modern online stock brokers have a feature called stop-loss, where you can enter a price at which your stocks automatically get sold if they drop down to that price. A trailing stop-loss order is similar, but instead of a fixed price, you enter a margin (e.g. 10%). If the stock price rises, the stop-loss price will trail upwards by that margin. For example, if you buy a share at 100 euros and it has risen to 110 euros, you can set a 10% trailing stop-loss order which automatically sells it if the price drops 10% from the peak of 110 euros, at 99 euros. Thus, no matter what happens, you only lost 1 euro. And if the stock price continues to rise to 150 euros, the trailing stop-loss would automatically readjust to 150 euros minus 10%, which is 135 euros (150-15=135). If the price dropped to 135 euros, you would lock in a gain of 35 euros, which is not the peak price of 150 euros, but still better than whatever the price fell down to as a result of a large crash. In the simple case above, it obviously makes sense in theory, but it might not make sense in practice. Prices constantly oscillate, so you don t want a margin that is too small, otherwise you exit too early. Conversely, having a large margin may result in too large a drawdown before exiting. If markets crash rapidly, it might be that nobody buys your stocks at the stop-loss price, and shares have to be sold at an even lower price. Also, what will you do once the position is sold? The reason you invested in the stock market was to avoid holding cash, so would you buy the same stock back when the crash bottoms? But how will you know when the bottom has been reached?

Backtesting stock market strategies with Python, YFinance, Pandas and Lightweight Charts I am not a professional investor, and nobody should take investment advice from me. However, I know what backtesting is and how to leverage open source software. So, I wrote a Python script to test if the trading strategy of using trailing stop-loss orders with specific margin values would have worked for a particular stock. First you need to have data. YFinance is a handy Python library that can be used to download the historic price data for any stock ticker on Yahoo.com. Then you need to manipulate the data. Pandas is the Python data analysis library with advanced data structures for working with relational or labeled data. Finally, to visualize the results, I used Lightweight Charts, which is a fast, interactive library for rendering financial charts, allowing you to plot the stock price, the trailing stop-loss line, and the points where trades would have occurred. I really like how the zoom is implemented in Lightweight Charts, which makes drilling into the data points feel effortless. The full solution is not polished enough to be published for others to use, but you can piece together your own by reusing some of the key snippets. To avoid re-downloading the same data repeatedly, I implemented a small caching wrapper that saves the data locally (as Parquet files):

python Copy

CACHE_DIR.mkdir(parents=True, exist_ok=True) end_date = datetime.today().strftime("%Y-%m-%d") cache_file = CACHE_DIR / f" TICKER - START_DATE -- end_date .parquet" if cache_file.is_file(): dataframe = pandas.read_parquet(cache_file) print(f"Loaded price data from cache: cache_file ") else: dataframe = yfinance.download( TICKER, start=START_DATE, end=end_date, progress=False, auto_adjust=False ) dataframe.to_parquet(cache_file) print(f"Fetched new price data from Yahoo Finance and cached to: cache_file ")

CACHE_DIR.mkdir(parents=True, exist_ok=True)
end_date = datetime.today().strftime("%Y-%m-%d")
cache_file = CACHE_DIR / f" TICKER - START_DATE -- end_date .parquet"

if cache_file.is_file():
 dataframe = pandas.read_parquet(cache_file)
 print(f"Loaded price data from cache:  cache_file ")
else:
 dataframe = yfinance.download(
 TICKER,
 start=START_DATE,
 end=end_date,
 progress=False,
 auto_adjust=False
 )

 dataframe.to_parquet(cache_file)
 print(f"Fetched new price data from Yahoo Finance and cached to:  cache_file ")

The dataframe is a Pandas object with a powerful API. For example, to print a snippet from the beginning and the end of the dataframe to see what the data looks like, you can use:

python Copy

print("First 5 rows of the raw data:") print(df.head()) print("Last 5 rows of the raw data:") print(df.tail())

print("First 5 rows of the raw data:")
print(df.head())
print("Last 5 rows of the raw data:")
print(df.tail())

Example output:

Copy

First 5 rows of the raw data Price Adj Close Close High Low Open Volume Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA Date 2014-01-02 29.956285 55.540001 56.910000 55.349998 56.700001 316552 2014-01-03 30.031801 55.680000 55.990002 55.290001 55.580002 210044 2014-01-06 30.080338 55.770000 56.230000 55.529999 55.560001 185142 2014-01-07 30.943321 57.369999 57.619999 55.790001 55.880001 370397 2014-01-08 31.385597 58.189999 59.209999 57.750000 57.790001 489940 Last 5 rows of the raw data Price Adj Close Close High Low Open Volume Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA Date 2025-12-11 78.669998 78.669998 78.919998 76.900002 76.919998 357918 2025-12-12 78.089996 78.089996 80.269997 78.089996 79.470001 280477 2025-12-15 79.080002 79.080002 79.449997 78.559998 78.559998 233852 2025-12-16 78.860001 78.860001 79.980003 78.809998 79.430000 283057 2025-12-17 80.080002 80.080002 80.150002 79.080002 79.199997 262818

First 5 rows of the raw data
Price Adj Close Close High Low Open Volume
Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA
Date
2014-01-02 29.956285 55.540001 56.910000 55.349998 56.700001 316552
2014-01-03 30.031801 55.680000 55.990002 55.290001 55.580002 210044
2014-01-06 30.080338 55.770000 56.230000 55.529999 55.560001 185142
2014-01-07 30.943321 57.369999 57.619999 55.790001 55.880001 370397
2014-01-08 31.385597 58.189999 59.209999 57.750000 57.790001 489940
Last 5 rows of the raw data
Price Adj Close Close High Low Open Volume
Ticker BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA BNP.PA
Date
2025-12-11 78.669998 78.669998 78.919998 76.900002 76.919998 357918
2025-12-12 78.089996 78.089996 80.269997 78.089996 79.470001 280477
2025-12-15 79.080002 79.080002 79.449997 78.559998 78.559998 233852
2025-12-16 78.860001 78.860001 79.980003 78.809998 79.430000 283057
2025-12-17 80.080002 80.080002 80.150002 79.080002 79.199997 262818

Adding new columns to the dataframe is easy. For example, I used a custom function to calculate the Relative Strength Index (RSI). To add a new column RSI with a value for every row based on the price from that row, only one line of code is needed, without custom loops:

python Copy

df["RSI"] = compute_rsi(df["price"], period=14)

df["RSI"] = compute_rsi(df["price"], period=14)

After manipulating the data, the series can be converted into an array structure and printed as JSON into a placeholder in an HTML template:

python Copy

baseline_series = [ "time": ts, "value": val for ts, val in df_plot[["timestamp", BASELINE_LABEL]].itertuples(index=False) ] baseline_json = json.dumps(baseline_series) template = jinja2.Template("template.html") rendered_html = template.render( title=title, heading=heading, description=description_html, ... baseline_json=baseline_json, ... ) with open("report.html", "w", encoding="utf-8") as f: f.write(rendered_html) print("Report generated!")

 baseline_series = [
  "time": ts, "value": val 
 for ts, val in df_plot[["timestamp", BASELINE_LABEL]].itertuples(index=False)
 ]

 baseline_json = json.dumps(baseline_series)
 template = jinja2.Template("template.html")
 rendered_html = template.render(
 title=title,
 heading=heading,
 description=description_html,
 ...
 baseline_json=baseline_json,
 ...
 )

 with open("report.html", "w", encoding="utf-8") as f:
 f.write(rendered_html)
 print("Report generated!")

In the HTML template, the marker variable in Jinja syntax gets replaced with the actual JSON:

html Copy

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title> title </title> ... </head> <body> <h1> heading </h1> <div id="chart"></div> <script> // Ensure the DOM is ready before we initialise the chart document.addEventListener('DOMContentLoaded', () => // Parse the JSON data passed from Python const baselineData = baseline_json safe ; const strategyData = strategy_json safe ; const markersData = markers_json safe ; // Create the chart const chart = LightweightCharts.createChart(document.getElementById('chart'), width: document.getElementById('chart').clientWidth, height: 500, layout: background: color: "#222" , textColor: "#ccc" , grid: vertLines: color: "#555" , horzLines: color: "#555" ); // Add baseline series const baselineSeries = chart.addLineSeries( title: ' baseline_label ', lastValueVisible: false, priceLineVisible: false, priceLineWidth: 1 ); baselineSeries.setData(baselineData); baselineSeries.priceScale().applyOptions( entireTextOnly: true ); // Add strategy series const strategySeries = chart.addLineSeries( title: ' strategy_label ', lastValueVisible: false, priceLineVisible: false, color: '#FF6D00' ); strategySeries.setData(strategyData); // Add buy/sell markers to the strategy series strategySeries.setMarkers(markersData); // Fit the chart to show the full data range (full zoom) chart.timeScale().fitContent(); ) </script> </body> </html>

<!DOCTYPE html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <title>  title  </title>
 ...
</head>
<body>
 <h1>  heading  </h1>
 <div id="chart"></div>
 <script>
 // Ensure the DOM is ready before we initialise the chart
 document.addEventListener('DOMContentLoaded', () =>  
 // Parse the JSON data passed from Python
 const baselineData =   baseline_json   safe  ;
 const strategyData =   strategy_json   safe  ;
 const markersData =   markers_json   safe  ;

 // Create the chart
 const chart = LightweightCharts.createChart(document.getElementById('chart'),  
 width: document.getElementById('chart').clientWidth,
 height: 500,
 layout:  
 background:   color: "#222"  ,
 textColor: "#ccc"
  ,
 grid:  
 vertLines:   color: "#555"  ,
 horzLines:   color: "#555"  
  
  );

 // Add baseline series
 const baselineSeries = chart.addLineSeries( 
 title: '  baseline_label  ',
 lastValueVisible: false,
 priceLineVisible: false,
 priceLineWidth: 1
  );
 baselineSeries.setData(baselineData);

 baselineSeries.priceScale().applyOptions( 
 entireTextOnly: true
  );

 // Add strategy series
 const strategySeries = chart.addLineSeries( 
 title: '  strategy_label  ',
 lastValueVisible: false,
 priceLineVisible: false,
 color: '#FF6D00'
  );
 strategySeries.setData(strategyData);

 // Add buy/sell markers to the strategy series
 strategySeries.setMarkers(markersData);

 // Fit the chart to show the full data range (full zoom)
 chart.timeScale().fitContent();
  )
 </script>
</body>
</html>

There are also Python libraries built specifically for backtesting investment strategies, such as Backtrader and Zipline, but they do not seem to be actively maintained, and probably have too many features and complexity compared to what I needed for doing this simple test. The screenshot below shows an example of backtesting a strategy on the Waste Management Inc stock from January 2015 to December 2025. The baseline Buy and hold scenario is shown as the blue line and it fully tracks the stock price, while the orange line shows how the strategy would have performed, with markers for the sells and buys along the way.

Results I experimented with multiple strategies and tested them with various parameters, but I don t think I found a strategy that was consistently and clearly better than just buy-and-hold. It basically boils down to the fact that I was not able to find any way to calculate when the crash has bottomed based on historical data. You can only know in hindsight that the price has stopped dropping and is on a steady path to recovery, but at that point it is already too late to buy in. In my testing, most strategies underperformed buy-and-hold because they sold when the crash started, but bought back after it recovered at a slightly higher price. In particular when using narrow margins and selling on a 3-6% drawdown the strategy performed very badly, as those small dips tend to recover in a few days. Essentially, the strategy was repeating the pattern of selling 100 stocks at a 6% discount, then being able to buy back only 94 shares the next day, then again selling 94 shares at a 6% discount, and only being able to buy back maybe 90 shares after recovery, and so forth, never catching up to the buy-and-hold. The strategy worked better in large market crashes as they tended to last longer, and there were higher chances of buying back the shares while the price was still low. For example, in the 2020 crash selling at a 20% drawdown was a good strategy, as the stock I tested dropped nearly 50% and remained low for several weeks; thus, the strategy bought back the stocks while the price was still low and had not yet started to climb significantly. But that was just a lucky incident, as the delta between the trailing stop-loss margin of 20% and total crash of 50% was large enough. If the crash had been only 25%, the strategy would have missed the rebound and ended up buying back the stocks at a slightly higher price. Also, note that the simulation assumes that the trade itself is too small to affect the price formation. We should keep in mind that in reality, if many people have stop-loss orders in place, a large price drop would trigger all of them, creating a flood of sell orders, which in turn would affect the price and drive it lower even faster and deeper. Luckily, it seems that stop-loss orders are generally not a good strategy, and we don t need to fear that too many people will be using them.

Conclusion Even though using a trailing stop-loss strategy does not seem to help in getting consistently higher returns based on my backtesting, I would still say it is useful in protecting from the downside of stock investing. It can act as a kind of insurance policy to considerably decrease the chances of losing big while increasing the chances of losing a little bit. If you are risk-averse, which I think I probably am, this tradeoff can make sense. I d rather miss out on an initial 50% loss and an overall 3% gain on recovery than have to sit through weeks or months with a 50% loss before the price recovers to prior levels. Most notably, the trailing stop-loss strategy works best if used only once. If it is repeated multiple times, the small losses in gains will compound into big losses overall. Thus, I think I might actually put this automation in place at least on the stocks in my portfolio that have had the highest gains. If they keep going up, I will ride along, but once the crash happens, I will be out of those particular stocks permanently. Do you have a favorite open source investment tool or are you aware of any strategy that actually works? Comment below!

A new release of my mixed collection of things package dang package arrived at CRAN earlier today. The dang package regroups a few functions of mine that had no other home as for example lsos() from a StackOverflow question from 2009 (!!), the overbought/oversold price band plotter from an older blog post, the market monitor blogged about as well as the checkCRANStatus() function tweeted about by Tim Taylor. And more so take a look. This release retires two functions: the social media site nobody ever visits anymore shut down its API too, so no way to mute posts by a given handle. Similarly, the (never official) ability by Google to supply financial data is no more, so the function to access data this way is gone too. But we also have two new ones: one that helps with CRAN entries for ORCiD ids, and another little helper to re-order microbenchmark results by summary column (defaulting to the median). Other than the usual updates to continuous integrations, as well as a switch to Authors@R which will result in CRAN nagging me less about this, and another argument update. The detailed NEWS entry follows.

Changes in version 0.0.17 (2025-12-18)

• Added new funtion reorderMicrobenchmarkResults with alias rmr
• Use tolower on email argument to checkCRANStatus
• Added new function cranORCIDs bootstrapped from two emails by Kurt Hornik
• Switched to using Authors@R in DESCRIPTION and added ORCIDs where available
• Switched to r-ci action with included bootstrap step; updated updated the checkout action (twice); added (commented-out) log accessor
• Removed googleFinanceData as the (unofficial) API access point no longer works
• Removed muteTweeters because the API was turned off

Via my CRANberries, there is a comparison to the previous release. For questions or comments use the the issue tracker at the GitHub repo.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. If you like this or other open-source work I do, you can sponsor me at GitHub.

21 years ago today I wrote my first blog post. Did I think I d still be writing all this time later? I ve no idea to be honest. I ve always had the impression my readership is small, and people who mostly know me in some manner, and I post to let them know what I m up to in more detail than snippets of IRC conversation can capture. Or I write to make notes for myself (I frequently refer back to things I ve documented here). I write less about my personal life than I used to, but I still occasionally feel the need to mark some event. From a software PoV I started out with Blosxom, migrated to MovableType in 2008, ditched that, when the Open Source variant disappeared, for Jekyll in 2015 (when I also started putting it all in git). And have stuck there since. The static generator format works well for me, and I outsource comments to Disqus - I don t get a lot, I can t be bothered with the effort of trying to protect against spammers, and folk who don t want to use it can easily email or poke me on the Fediverse. If I ever feel the need to move from Jekyll I ll probably take a look at Hugo, but thankfully at present there s no push factor to switch. It s interesting to look at my writing patterns over time. I obviously started keen, and peaked with 81 posts in 2006 (I ve no idea how on earth that happened), while 2013 had only 2. Generally I write less when I m busy, or stressed, or unhappy, so it s kinda interesting to see how that lines up with various life events. During that period I ve lived in 10 different places (well, 10 different houses/flats, I think it s only 6 different towns/cities), on 2 different continents, working at 6 different employers, as well as a period where I was doing my Masters in law. I ve travelled around the world, made new friends, lost contact with folk, started a family. In short, I have lived, even if lots of it hasn t made it to these pages. At this point, do I see myself stopping? No, not really. I plan to still be around, like Flameeyes, to the end. Even if my posts are unlikely to hit the frequency from back when I started out.