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  ▘▘ ▝▝    X:\gp\common\tests

   Opus 4.8 is here! Now defaults to high effort · /effort xhigh for your hardest tasks

> I need a stress test for GpEventBus. It should be part of the                 
  @tests\testGpEventBus.dpr project.                                            
                                                                                
  Please examine GpEventBus.md and GpEventBus.pas and devise a spec for a       
  stress test.                                                                  
  ⎿  Read tests\testGpEventBus.dpr (14 lines)

● I'll start by invoking the brainstorming skill since you're asking me to
  devise a spec — that's design work. Let me also read the relevant files in
  parallel.

● Skill(superpowers:brainstorming)
  ⎿  Successfully loaded skill

  Read 2 files (ctrl+o to expand)

● Let me explore the implementation to ground the stress-test design in how the
  bus actually works.

  Read 1 file (ctrl+o to expand)

● I've now read the full implementation. A few things stand out that should
  shape the stress test:

  - The version history (1.01→1.06) is almost entirely memory-safety and 
  shutdown-race fixes around QueueUserAPC ref-counting, dead-thread detection,
  and threads terminating without UnregisterThread. That's the highest-value
  area to stress.
  - The bounded TThreadedQueue (default depth 1024, 100 ms push timeout) means
  queue overflow under high fire rates will raise in DispatchToBackgroundThread.
  - The existing project is an interactive VCL GUI with manual buttons — no
  automated/programmatic stress path exists yet.
  - DEBUG builds add the alertable-wait monitor (5 s) and DebugBreak traps,
  which interact with rapid thread churn.

  Before I design the spec, I have a few things to pin down. I'll go one
  question at a time.

● User answered Claude's questions:
  ⎿  · How should the stress test be driven within the existing 
     testGpEventBus.dpr GUI project? → New "Stress Test" tab

● New "Stress Test" tab it is. Next: which scenarios matter most to you. The
  implementation's risk areas suggest several; I want to know which to
  prioritize (you can pick several).
  ⎿  Invalid tool parameters

● User declined to answer questions
  ⎿  · Which stress scenarios should the test exercise? (pick all that apply) 
     (High-throughput dispatch / Subscribe/unsubscribe churn / Thread lifecycle 
     churn / Queue overflow)

● It looks like you selected all four scenarios but want to clarify something
  first. What would you like to discuss or clarify about these scenarios before
  we lock them in?

✻ Crunched for 1m 12s

> I would like to test four scenarios separately - so please make a button to   
  start each scenario manually.                                                 

● Got it — four independent scenarios, each with its own Start button, running
  and reporting pass/fail on its own. That changes the tab layout from one
  runner to four scenario panels.

  Now an important interaction I want your call on. The Thread lifecycle churn
  scenario includes threads that terminate without calling UnregisterThread —
  that's exactly what exercises the 1.04–1.06 ref-count/leak fixes. But in DEBUG
  builds the bus deliberately fights that misuse: APCProc and Destroy emit
  OutputDebugString + DebugBreak when an APC fires (or the bus is destroyed) for
  a thread with zero subscriptions, and RegisterThread arms a 5-second
  alertable-wait watchdog that raises if tripped. A DebugBreak with no debugger
  attached can itself crash the process.

  So the abrupt-termination path means something different per build:

● User answered Claude's questions:
  ⎿  · How should the stress test handle DEBUG-mode diagnostics vs the 
     abrupt-termination (no UnregisterThread) path? → Target RELEASE for leak 
     runs

● RELEASE for the leak runs — and I'll note in the spec that DEBUG is the build
  where the diagnostics themselves can be observed firing.

  Next: which bus instance each scenario runs against.

● User answered Claude's questions:
  ⎿  · Should each scenario run against its own isolated bus instance, or the 
     global EventBus singleton? → Isolated per run (Recommended)

● Here's the design. I've organized it into sections — tell me where it looks
  right and where you'd adjust.

  1. Integration & file layout

  - New tab tsStress added to PageControl1, built programmatically in code (a
  BuildStressTab method called from FormCreate) rather than by hand-editing the
  .dfm — safer for the four-panel layout and avoids .dfm merge risk.
  - New unit testGpEventBusStress.pas added to the .dpr, holding the stress
  event types, worker/producer thread classes, and four scenario-controller 
  classes. The tab is a thin UI that starts/stops controllers and polls their
  atomic counters. (This keeps the already-large testGpEventBusMain.pas focused
  — the controllers are VCL-free except for callback reporting, not a separate
  headless engine.)
  - testGpEventBus.dpr: set ReportMemoryLeaksOnShutdown := True.

  2. Tab layout — four independent panels

  Each scenario gets its own TGroupBox with: a few param edits (defaults filled
  in), a Start and Stop button, live stat labels, and a verdict label (RUNNING /
  PASS green / FAIL red). A shared results memo at the bottom logs each run's
  start/stop/verdict. A dedicated TTimer refreshes the live stats from atomic
  counters. Each scenario is time-boxed by a Duration edit and also stoppable
  manually; Start disables itself while running.

  3. Common accounting model

  - Every fired event carries a ProducerID, a monotonic Sequence, and a Checksum
  (derived from the payload). Subscribers validate the checksum on receipt →
  catches corruption/torn copies across the thread boundary.
  - Atomic (TInterlocked) counters: Fired, Received, Dropped, ChecksumErrors,
  Exceptions.
  - Each scenario runs against its own CreateEventBus instance, freed in a
  finally at scenario end (exercises the Destroy shutdown paths).
  Worker/producer threads take the bus as a constructor parameter.
  - Subscriber handlers created in loops use a MakeHandler helper method that 
  captures by value (per the closure-capture rule), never loop variables.

  4. The four scenarios

  A. High-throughput dispatch — N producers (default 4) fire 3 event types as
  fast as possible into M registered subscriber threads (default 8) + 1
  main-thread subscriber. Uses a generous queue depth so overflow doesn't happen
  here (overflow is scenario D). After Stop: stop producers, drain,
  unsubscribe, unregister, free bus. PASS = Received == Fired × subscriberCount,
  zero checksum errors, zero exceptions, zero queue-push failures, no leak.

  B. Subscribe/unsubscribe churn — a steady producer load runs while churn
  threads repeatedly Subscribe/Unsubscribe (and occasionally UnsubscribeAll<T>)
  on their registered threads. PASS = no crash, zero checksum errors on
  delivered events, zero exceptions, and final SubscriptionCount<T> == 0 after
  cleanup. (Event totals are best-effort here since handlers come and go —
  integrity + clean teardown is the invariant.)

  C. Thread lifecycle churn — continuously spawn workers that RegisterThread →
  Subscribe → brief alertable wait → exit, while producers fire into them. A
  configurable fraction exit abruptly without UnregisterThread (guarded so the
  abrupt path is RELEASE-meaningful; clean path keeps DEBUG quiet). Targets
  DetectAndRemoveDeadThreads and the 1.04–1.06 never-balanced-APC-ref fix. PASS
  = no crash/AV, process stable, no leak at bus Destroy.

  D. Queue overflow — CreateEventBus(64) (small depth), 1+ deliberately slow 
  subscriber (handler Sleeps), fast producers flooding it. The bounded
  TThreadedQueue push times out → DispatchToBackgroundThread raises → Fire
  swallows it (counted as Dropped) → backpressure, no crash. PASS = process
  survives, overflow actually occurred (Dropped > 0), delivered events intact
  and in per-producer order, no leak.

  5. Leak verification

  Primary mechanism is ReportMemoryLeaksOnShutdown — run a scenario, close the
  app, confirm no leak dialog. I'll note in the spec that the leak-sensitive
  scenarios (C especially) are meant to be run in a RELEASE build, since DEBUG's
  DebugBreak/watchdog intentionally trip on the abrupt path.

  ---
  Does this match what you have in mind — particularly the per-scenario PASS
  criteria and the queue-overflow "graceful drop" expectation? Anything to add,
  cut, or re-tune before I write it up as a spec?

✻ Brewed for 2m 6s

> Yes, this is great. Please write a spec.                                      
● Write(X:\gp\common\docs\superpowers\specs\2026-05-29-gpeventbus-stress-test-de
       sign.md)
  ⎿  Wrote 272 lines to
     ..\docs\superpowers\specs\2026-05-29-gpeventbus-stress-test-design.md
       2 # GpEventBus Stress Test — Design Spec
       3 **Date:** 2026-05-29
       4 **Component:** `tests\testGpEventBus.dpr` (interactive VCL test 
       5 **Status:** Approved for planning
       6 
       7 ## Goal
       9 Add an automated, button-driven stress test for `GpEventBus` to 
         the existing
      10 `testGpEventBus.dpr` project. The stress test exercises the bus 
         under heavy
     … +399 lines (ctrl+o to expand)

● Spec written to X:\gp\common\docs\superpowers\specs\2026-05-29-gpeventbus-stre
  ss-test-design.md.

  I ran a self-review pass: no placeholders/TBDs (the "Open questions" are
  deliberate, with stated defaults), the four scenarios' PASS criteria are
  internally consistent with the accounting model, and scope stays within the
  public API with no GpEventBus.pas changes.

  Two notes:
  - I did not auto-commit. This tree is on the X: drive → SVN, not git, and
  committing is your call — let me know if you'd like me to svn add + commit it.
  - The spec records the build-mode split (RELEASE for clean leak runs, DEBUG to
  observe diagnostics firing) and the closure-capture MakeHandler requirement,
  per your standards.

  Please review the spec and let me know if you want any changes before I move
  on to writing the implementation plan.

✻ Cooked for 1m 23s

> Looks good, please proceed. Do NOT commit anything.                           

● Skill(superpowers:writing-plans)
  ⎿  Successfully loaded skill

● I'm using the writing-plans skill to create the implementation plan.

  Let me quickly check the build setup so the plan's compile/verify steps are
  concrete.

  Searched for 1 pattern, listed 1 directory (ctrl+o to expand)

● I'm using the writing-plans skill to create the implementation plan.

  One note up front: the project has no command-line-runnable assertion harness
  for the GUI app (the separate testGpEventBusDUnit.dpr is the DUnitX project;
  the user wants this in the GUI testGpEventBus.dpr). So per-task verification
  is clean compile (via the delphi-compile skill) plus a final manual RELEASE 
  run observing the on-screen verdicts. Tight type coupling between the base
  class, thread classes, and scenarios means the new unit is built as one
  cohesive task with bite-sized steps, compiled at the end.

  Let me look at the .dpr and .dproj reference list so the wiring steps are
  exact.

  Searched for 1 pattern, read 1 file (ctrl+o to expand)

● Now I'll write the plan.

● Write(X:\gp\common\docs\superpowers\plans\2026-05-29-gpeventbus-stress-test.md
       )
  ⎿  Wrote 1566 lines to
     ..\docs\superpowers\plans\2026-05-29-gpeventbus-stress-test.md
      2 # GpEventBus Stress Test Implementation Plan
        bagent-driven-development (recommended) or superpowers:executing-
        plans to implement this plan task-by-task. Steps use checkbox (`-
      4  [ ]`) syntax for tracking.
      5 **Goal:** Add a button-driven, four-scenario stress test for `GpE
        each scenario running against an isolated bus and reporting a PAS
      6 S/FAIL verdict.
      7 **Architecture:** A new unit `testGpEventBusStress.pas` holds str
         four scenario-controller classes derived from a common base (`TS
        tressScenario
     … +1794 lines (ctrl+o to expand)

● Plan complete and saved to
  docs\superpowers\plans\2026-05-29-gpeventbus-stress-test.md.

  It covers 5 tasks: (1) project wiring + skeleton unit, (2) the full
  testGpEventBusStress.pas — events, base scenario, thread classes, and all four
  scenario controllers, with complete compilable code, (3) the
  programmatically-built Stress Test tab + form integration, (4) docs, and (5) a
  manual RELEASE verification run with leak check. I ran the self-review pass:
  spec coverage maps to tasks, no placeholders, and type/name consistency holds
  (notably, Dropped is intentionally a derived verdict value since the bus
  swallows overflow internally — the producer can't observe a drop).

  Two execution options:

  1. Subagent-Driven (recommended) — I dispatch a fresh subagent per task and
  review between tasks. Fast iteration, good for a plan this size.

  2. Inline Execution — I execute the tasks in this session with checkpoints for
  your review.

  Which approach? (And to confirm: I'll honor your "do not commit anything"
  instruction throughout — verification is via clean compiles and the manual
  run, with no git/svn commits.)

✻ Baked for 9m 15s

> 1                                                                             

● Skill(superpowers:subagent-driven-development)
  ⎿  Successfully loaded skill

● I'm using Subagent-Driven Development to execute the plan. Let me read the
  prompt templates so my dispatches follow them, adapting for this environment
  (SVN — not git — and the explicit "no commits" instruction).

  Read 3 files (ctrl+o to expand)

● I'll execute the plan task-by-task with fresh subagents, adapting the workflow
  to this environment: no git (SVN working copy), no commits (per your
  instruction), no worktrees, and verification via the delphi-compile skill
  rather than a test harness. I'll run continuously through the tasks, reviewing
  each before moving on.

  Starting with Task 1 (project wiring + skeleton unit).

● Agent(Implement Task 1: project wiring)
  ⎿  Done (7 tool uses · 28.1k tokens · 33s)
  (ctrl+o to expand)

● Task 1 reports DONE with a clean compile. For a three-line wiring change
  verified by compilation, I'll do the spec check inline rather than spending
  two more subagents on it. Let me verify the actual files.

  Searched for 1 pattern, read 2 files (ctrl+o to expand)
● Task 1 verified — .dpr uses clause, ReportMemoryLeaksOnShutdown, skeleton
  unit, and .dproj reference all match spec, and it compiles clean. Marking
  complete.

  Now Task 2 — the full stress unit (events, base scenario, four thread classes,
  four scenario controllers). This is ~1000 lines of complete, verbatim Delphi
  in the plan. To avoid transcription drift, I'll have the implementer copy the
  code blocks directly from the plan file rather than re-typing from a prompt,
  with full scene-setting context.

● Agent(Implement Task 2: stress unit)
  ⎿  Done (16 tool uses · 76.8k tokens · 3m 32s)
  (ctrl+o to expand)

● Task 2 reports DONE_WITH_CONCERNS. The deviation is sound: the MakeHandlerN
  factory functions return TEventHandler<T>, so the call sites need () to invoke
  them — passing the bare method name is a genuine compile error in the plan's
  code, not a transcription slip. Good catch, and behavior-preserving. Both
  DEBUG and RELEASE compile clean.

  Now the spec-compliance review for this substantial unit. Dispatching an
  independent reviewer.

● Agent(Spec review Task 2)
  ⎿  Done (2 tool uses · 65.9k tokens · 32s)
  (ctrl+o to expand)

● Spec review: ✅ compliant — exact match to the plan with only the eight
  approved () fixes, and all correctness-critical details (DEBUG guard, verdict
  logic, subscriber-count math, atomic-read pattern) verified.

  Now the code-quality review. Since there are no git SHAs, I'll point the
  reviewer at the new file directly.

● feature-dev:code-reviewer(Code quality review Task 2)
  ⎿  Done (31 tool uses · 69.6k tokens · 5m 0s)
  (ctrl+o to expand)

● Code-quality review returned needs minor changes: two Important issues
  (non-thread-safe Random on the manager thread; FSubs.Clear not calling
  Unsubscribe) and three Minor ones. Evaluating them:

  - #1 Random race — valid; Random mutates global RandSeed unguarded. Fix with a
  per-instance xorshift. Apply.
  - #2 FSubs.Clear without Unsubscribe — valid; explicit unsubscribe matches
  ClearMainSubs and makes DEBUG counting exact. Apply.
  - #3 no-op drain comment — cheap clarity win. Apply.
  - #5 field-group blank line — trivial. Apply.
  - #4 TInterlocked.Add(x,0) → Read — purely cosmetic (reviewer confirms
  identical codegen), and the Integer overload is uncertain across the counters.
  Decline to avoid risk for zero behavior change.

  Dispatching the implementer fix.

● Agent(Fix Task 2 review issues)
  ⎿  Done (13 tool uses · 42.9k tokens · 1m 12s)
  (ctrl+o to expand)

● All four fixes applied; DEBUG and RELEASE both compile clean. Let me verify
  the changed regions directly.

  Searched for 1 pattern (ctrl+o to expand)

● All four fixes verified in place. Task 2 complete (spec ✅, quality fixes
  applied and confirmed, DEBUG+RELEASE compile clean).

  Now Task 3 — the Stress Test tab UI and form integration in
  testGpEventBusMain.pas. This modifies the existing form with specific
  insertion points; the plan has complete code.

● Agent(Implement Task 3: UI tab)
  ⎿  Done (12 tool uses · 66.9k tokens · 1m 44s)
  (ctrl+o to expand)

● Task 3 reports DONE, no deviations, compiles clean. Spec-compliance review
  next.

● Agent(Spec review Task 3)
  ⎿  Done (2 tool uses · 62.5k tokens · 30s)
  (ctrl+o to expand)

● Spec review: ✅ compliant — all six steps verbatim, existing form code intact,
  and the harmless record value-copy pattern correctly noted (it copies
  object/control references, so mutations land on the right controls).

  Code-quality review for the form changes:

● feature-dev:code-reviewer(Code quality review Task 3)
  ⎿  Done (3 tool uses · 36.4k tokens · 1m 6s)
  (ctrl+o to expand)

● Code-quality review for Task 3: needs one change. Evaluating:

  - #1 Timer reentrancy — real and worth fixing: the 200 ms timer keeps firing
  while Scenario.Stop pumps the message loop during its multi-second drain,
  re-entering StopScenario before FActive clears. Fix by disabling the timer
  across StopScenario. Apply.
  - #2 — reviewer retracted it. No action.
  - #3 Continue → continue — direct convention violation. Apply.
  - #5 frozen stats label after stop — cheap UX fix so the final numbers match
  the verdict. Apply.
  - #4 — not a real bug. Skip.

  Dispatching the fix.

● Agent(Fix Task 3 review issues)
  ⎿  Done (9 tool uses · 30.7k tokens · 52s)
  (ctrl+o to expand)

● Both fixes applied, compiles clean. Quick verification of the changed regions:

  Searched for 1 pattern (ctrl+o to expand)

● Verified — timer guard, final-stats refresh, and lowercase continue all in
  place. Task 3 complete (spec ✅, quality fixes applied and verified, compiles
  clean).

  Now Task 4 — documentation updates.

● Agent(Implement Task 4: docs)  ⎿  Done (4 tool uses · 38.2k tokens · 34s)
  (ctrl+o to expand)

● Task 4 reports DONE. Docs are lower-risk; I'll verify the insertions inline
  rather than spending reviewer subagents.

  Searched for 1 pattern, read 1 file (ctrl+o to expand)

● GpEventBus.md subsection is correctly placed (after the unit-test code block,
  before ## Thread Safety) and the table is well-formed; the testGpEventBus.md
  heading matches the existing ### N. **Name** (Tab N) style. Task 4 complete.

  Task 5 is a manual verification run (the user chose a GUI tab, by design).
  Before handing that off, I'll do the one part I can automate: confirm the
  fully-integrated project builds in the RELEASE configuration (the build needed
  for the leak runs, and the one that compiles the {$IFNDEF DEBUG} abrupt
  path). Let me build it myself.

● Skill(delphi-compile)
  ⎿  Successfully loaded skill

● Running a RELEASE-config build (no DEBUG defined, so the {$IFNDEF DEBUG}
  abrupt-termination path is compiled in):

● Bash(cd /x/gp/common/tests && "C:\Program Files
      (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U.. -$O+ -$D-
      testGpEventBus.dpr 2>&1 | tail -25)
  ⎿  Embarcadero Delphi for Win32 compiler version 37.0
     Copyright (c) 1983,2026 Embarcadero Technologies, Inc.
     Fatal: F1030 Invalid compiler directive: '--'

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      testGpEventBus.dpr 2>&1 | tail -25)
  ⎿  Embarcadero Delphi for Win32 compiler version 37.0
     Copyright (c) 1983,2026 Embarcadero Technologies, Inc.
     13217 lines, 0.17 seconds, 2267136 bytes code, 51740 bytes data.

● RELEASE-equivalent build (no DEBUG defined) succeeds — 0 errors, 0 warnings,
  exe produced, and the {$IFNDEF DEBUG} abrupt-termination path compiles in.
  Both DEBUG and RELEASE configs are confirmed good.

  That completes the automatable portion. Here's where things stand:

  Implementation complete (Tasks 1–4), verified by compile + two-stage review

  ┌──────┬────────────────────────────────────┬─────────────────────────────┐
  │ Task │                What                │           Status            │
  ├──────┼────────────────────────────────────┼─────────────────────────────┤
  │ 1    │ Wire new unit into .dpr/.dproj,    │ ✅ verified                 │
  │      │ enable ReportMemoryLeaksOnShutdown │                             │
  ├──────┼────────────────────────────────────┼─────────────────────────────┤
  │      │ testGpEventBusStress.pas — events, │ ✅ spec ✓ + quality fixes   │
  │ 2    │  base scenario, 5 thread classes,  │ (thread-safe RNG, explicit  │
  │      │ 4 controllers                      │ Unsubscribe) applied        │
  ├──────┼────────────────────────────────────┼─────────────────────────────┤
  │      │                                    │ ✅ spec ✓ + quality fixes   │
  │ 3    │ Stress Test tab + form wiring in   │ (timer-reentrancy guard,    │
  │      │ testGpEventBusMain.pas             │ final-stats refresh,        │
  │      │                                    │ lowercase continue) applied │
  ├──────┼────────────────────────────────────┼─────────────────────────────┤
  │ 4    │ GpEventBus.md + testGpEventBus.md  │ ✅ verified                 │
  │      │ docs                               │                             │
  └──────┴────────────────────────────────────┴─────────────────────────────┘

  Files changed (working copy only — no commits made, per your instruction):
  - tests\testGpEventBus.dpr, tests\testGpEventBus.dproj
  - tests\testGpEventBusStress.pas (new), tests\testGpEventBusMain.pas
  - GpEventBus.md, tests\testGpEventBus.md
  - Plus the spec and plan under docs\superpowers\

  Task 5 is yours to run — it needs the GUI

  I can't click Start buttons or read the on-screen verdicts/leak dialog, so I
  won't fabricate results. The exe is built. To verify:

  1. Build & run RELEASE (e.g. tests\testGpEventBus.exe from the build above, or
  rebuild Release in the IDE), open the Stress Test tab.
  2. Run each scenario (let it auto-stop on its Duration) and record the
  verdict:
    - A. Throughput → expect PASS, received == fired × (subscribers+1)
    - B. Churn → expect PASS, 0 subscriptions left
    - C. Lifecycle → expect PASS (no crash) — this is the key leak target
    - D. Overflow → expect PASS with dropped > 0 (overflow exercised)
  3. Close the app and confirm no memory-leak dialog appears.

  If scenario D shows no drops, raise its producer count or lower QueueDepth in
  DefaultOverflowConfig; if C reports a leak, that's a real finding to
  investigate.

  ---
  Two notes on the workflow tail: the subagent-driven skill normally ends with
  finishing-a-development-branch, but that's git merge/PR/cleanup — not 
  applicable here (SVN, no commits), so I've stopped at the working-copy changes
  for you to review and commit yourself. The substantive code (Tasks 2–3) went
  through both spec-compliance and code-quality review subagents; if you'd like,
  I can also run a final holistic review across the whole change set, or wire
  up a headless/console run mode so Task 5 can be automated in future.
  Otherwise, this is ready for your manual run.

✻ Crunched for 23m 40s

※ recap: Goal: add a button-driven stress test to testGpEventBus. Tasks 1–4 are done and compile clean in DEBUG and RELEASE; no commits were made. Next: you run the RELEASE GUI, click each scenario's Start, and confirm PASS verdicts plus no leak dialog on close. (disable recaps in /config)

> Reporting the results. Test A passes in 125 sec. Test B passes in 16 sec.     
  Test C passes in 22 sec, but shows two exception message boxes:               
                                                                                
  ---------------------------                                                   
  testgpeventbus                                                                
  ---------------------------                                                   
  Access violation at address 00CB5265 in module 'testGpEventBus.exe' (offset   
  205265). Read of address 00000010.                                            
  ---------------------------                                                   
  OK                                                                            
  ---------------------------                                                   
                                                                                
                                                                                
  ---------------------------                                                   
  testgpeventbus                                                                
  ---------------------------                                                   
  Invalid pointer operation.                                                    
  ---------------------------                                                   
  OK                                                                            
  ---------------------------                                                   
                                                                                
                                                                                
  When I close the app after that, I get:                                       
                                                                                
  ---------------------------                                                   
  Unexpected Memory Leak                                                        
  ---------------------------                                                   
  An unexpected memory leak has occurred. The unexpected small block leaks are: 
                                                                                
                                                                                
                                                                                
  1 - 12 bytes: TDictionary<System.Cardinal,GpEventBus.TEventBus.TThreadDispatc 
  hState>.TValueCollection x 1, TObject x 3                                     
                                                                                
  21 - 28 bytes: EMonitorLockException x 7, Exception x 127, TEventBus x 1      
                                                                                
  29 - 36 bytes: TEventBus.TThreadDispatchState x 1, Exception x 2,             
  EAccessViolation x 189                                                        
                                                                                
  37 - 44 bytes: EAccessViolation x 2                                           
                                                                                
  45 - 52 bytes: TObjectList<System.Classes.TThread> x 1,                       
  TDictionary<System.Cardinal,GpEventBus.TEventBus.TThreadDispatchState> x 1    
                                                                                
  53 - 60 bytes: TLifecycleWorkerThread x 1260, UnicodeString x 1               
                                                                                
  61 - 68 bytes: TLifecycleWorkerThread x 1,                                    
  TThreadedQueue<System.SysUtils.TProc> x 1, Unknown x 68                       
                                                                                
  77 - 84 bytes: TLifecycleManagerThread x 1                                    
                                                                                
  189 - 204 bytes: UnicodeString x 32                                           
                                                                                
  205 - 220 bytes: UnicodeString x 97                                           
                                                                                
  221 - 236 bytes: UnicodeString x 189                                          
                                                                                
  237 - 252 bytes: UnicodeString x 3                                            
                                                                                
  381 - 412 bytes: Unknown x 1                                                  
                                                                                
                                                                                
                                                                                
  The sizes of unexpected leaked medium and large blocks are: 262188, 7980      
                                                                                
                                                                                
  ---------------------------                                                   
  OK                                                                            
  ---------------------------                                                   
                                                                                

● Scenario C found real bugs — an access violation, an invalid-pointer
  (double-free) operation, and a large leak (notably ~1260 
  TLifecycleWorkerThread + the manager + the bus all leaked, meaning teardown
  crashed partway). This is exactly the kind of defect the stress test was built
  to surface. Before proposing any fix, I'll debug it systematically.

● Skill(superpowers:systematic-debugging)
  ⎿  Successfully loaded skill

● This is a real defect surfaced by the stress test, and I can't step through
  the GUI interactively — so per Phase 1 (reproduce consistently), I'll build a
  headless console reproduction of scenario C's pattern that I can run from the
  command line and bisect. My code reading already flags a strong suspect in
  GpEventBus itself: OS thread-ID reuse. After an abrupt worker dies without
  UnregisterThread, its TThreadDispatchState stays in FThreadStates keyed by
  thread ID; when Windows recycles that ID for a new worker, RegisterThread's if
  FThreadStates.ContainsKey(threadID) then Exit silently reuses the dead
  thread's state (with a stale thread handle). I need to confirm this
  empirically rather than guess.

  Let me gather the exact current worker/manager code, then write the repro.

  Read 1 file (ctrl+o to expand)

● Now I'll write a headless console reproduction mirroring scenario C, which I
  can run and bisect.

● Write(reproC.dpr)
  ⎿  Wrote 217 lines to reproC.dpr
       2 program reproC;
       3 {$APPTYPE CONSOLE}
       5 // Headless reproduction of stress scenario C (thread-lifecycle 
         churn) to root-cause
       6 // the access violation / invalid-pointer / leak seen in the GUI
       7 // Compile WITHOUT DEBUG (release-like) so the abrupt-exit path 
         is active:
       9 // Bisect with command-line switches:
      10 //   reproC                 -> full repro (producers + 50% abrup
         t)
     … +219 lines (ctrl+o to expand)

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr 2>&1 | tail -5)
  ⎿  Embarcadero Delphi for Win32 compiler version 37.0
     Copyright (c) 1983,2026 Embarcadero Technologies, Inc.
     11508 lines, 0.45 seconds, 1000324 bytes code, 43804 bytes data.

● Bash(./reproC.exe 2>&1; echo "EXITCODE=$?")
  ⎿  reproC: producers=True abrupt=0,50 duration=5000ms cap=8
     spawned 821 workers; fired=258922 received=1478211; stopping...
     worker fatal exceptions: 9  first: EAccessViolation: Access violation
     … +10 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Reproduced consistently — exact match to the GUI symptoms: EAccessViolation
  "Read of address 0x10", followed by EInvalidPointer (Invalid pointer
  operation), plus worker fatal AVs. Now I'll bisect (abrupt vs producers) and
  build a detailed map to decode the fault address.

● Bash(echo "=== noabrupt (all clean UnregisterThread) ==="; ./reproC.exe
      noabrupt 2>&1; echo "EXIT=$?"; echo; echo "=== noproducers (churn only, no
      Fire) ==="; ./repr…)  ⎿  === noabrupt (all clean UnregisterThread) ===
     reproC: producers=True abrupt=0,00 duration=5000ms cap=8
     spawned 745 workers; fired=641878 received=2446810; stopping...
     … +20 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -GD
      -U.. reproC.dpr >nul 2>&1; ls -la reproC.map 2>&1 | head -2)
  ⎿  -rw-r--r-- 1 gabr 197121 1175555 Jun  1 09:19 reproC.map

● Decisive bisection:
  - noabrupt still crashes — so abrupt termination is not required; clean
  UnregisterThread churn crashes too.
  - noproducers is clean — so concurrent Fire (APC dispatch) is required.

  The worker-thread AVs point at APCProc (which runs on worker threads). Let me
  get the fault address from the map-enabled build and decode it.

● Bash(./reproC.exe 2>&1 | grep -i "address\|invalid" | head -4)
  ⎿  worker fatal exceptions: 78  first: EAccessViolation: Access violation
      at address 00938D72 in module 'reproC.exe' (offset 8D72). Read of add
     ress 000003E8
     … +5 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Decoding via the map. Runtime fault offset E625D (bus-free AV) and 8D72
  (worker AV) map to segment-0001 offsets E525D and 7D72 (code RVA 0x1000). Let
  me find the enclosing symbols.

  Searched for 1 pattern (ctrl+o to expand)

● Bus-free AV (E525D) lands inside TThreadedQueue<TProc>.PopItem — i.e.,
  TEventBus.Destroy draining state.EventQueue.PopItem hits a corrupted/freed
  queue. Now the worker-side AV (7D72) and the EInvalidPointer (7C81):

  Searched for 2 patterns (ctrl+o to expand)

● Maps decode cleanly: the worker-side AV is in TObject.Free (freeing a bad
  reference), the EInvalidPointer is in TObject.FreeInstance (double-free), and
  the bus-free AV is in TThreadedQueue.PopItem over a dangling state. So:
  concurrent Fire + register/subscribe/unregister churn causes a use-after-free 
  / double-free of TThreadDispatchState — a pre-existing concurrency defect in
  GpEventBus.pas. To get the exact call stack rather than infer it, let me try a
  non-interactive debugger.

● Bash(for p in cdb.exe "/c/Program Files (x86)/Windows
      Kits/10/Debuggers/x64/cdb.exe" "/c/Program Files/Windows
      Kits/10/Debuggers/x64/cdb.exe"; do command -v "$p" >/d…)
  ⎿  FOUND: /c/Program Files (x86)/Windows Kits/10/Debuggers/x64/cdb.exe
     FILE: /c/Program Files (x86)/Windows Kits/10/Debuggers/x64/cdb.exe
     Redist
     … +7 lines (ctrl+o to expand)

● cdb (x86) is available. Let me run reproC under it, break on the first-chance
  access violation, and capture the native stack — frame offsets map back
  through reproC.map.

● Bash("/c/Program Files (x86)/Windows Kits/10/Debuggers/x86/cdb.exe" -c "sxe
      av; g; kv 40; q" reproC.exe 2>&1 | grep -iE
      "reproC\+0x|child-sp|ChildEBP|Access viol|fir…)
  ⎿  (No output)

● Bash("/c/Program Files (x86)/Windows Kits/10/Debuggers/x86/cdb.exe" -c "sxe
      av; g; r; kb 40; q" reproC.exe > cdb.out 2>&1; echo "---- size:"; wc -l
      cdb.out; echo "--…)
  ⎿  ---- size:
     9 cdb.out
     ---- stack region:
     … +2 lines (ctrl+o to expand)

● Bash("/c/Program Files (x86)/Windows Kits/10/Debuggers/x86/cdb.exe" -c "sxe
      av; g; r; kb 50; q" "X:\gp\common\tests\reproC.exe" > cdb.out 2>&1; echo
      "lines:"; wc -l…)
  ⎿  lines:
     71 cdb.out
     === stack ===
     … +12 lines (ctrl+o to expand)
  ⎿  (timeout 1m)

  Read 1 file (ctrl+o to expand)

● Now I have a real stack. Module base 0x00930000; faulting EIP reproC+0x99ef
  (mov edx,[eax], eax=0x3e8 — dereferencing a freed/garbage pointer), and
  crucially frame ntdll!KiUserApcDispatcher → the AV is inside an APC callback
  (APCProc), with the immediate caller at reproC+0xE63DB which sits inside
  TThreadedQueue.PopItem. Let me name the faulting function (seg offset 0x89EF).

● Bash(echo "=== faulting fn near seg 0x89EF ==="; grep -oE
      "0001:0000(8[0-9A-F]{2}) +[^ ].*" reproC.map | sort -u | awk '{print $1,
      $2}' | grep -iE "0001:000089|0001:…)
  ⎿  === faulting fn near seg 0x89EF ===
     --- broader 0x88-0x8A ---

  Searched for 2 patterns (ctrl+o to expand)

● I have the root cause, with hard evidence. Let me summarize before deciding
  next steps.

  Root cause (confirmed, not inferred)

  The stress test did its job — it found a genuine, pre-existing concurrency bug
  in GpEventBus.pas itself.

  Evidence chain:
  - Consistent headless repro (tests\reproC.dpr, public API only, documented
  usage) reproduces the GUI symptoms exactly: EAccessViolation "Read of address
  0x10", EInvalidPointer, worker AVs.
  - Bisection:
    - noproducers (churn, no Fire) → clean, no crash.
    - noabrupt (all workers UnregisterThread cleanly, alertable waits — fully
  compliant usage) → still crashes.
    - ⇒ Trigger = concurrent Fire (QueueUserAPC dispatch) + thread 
  register/subscribe/unregister churn. Abrupt termination is not required; this
  is not misuse.
  - cdb stack at first fault: ntdll!KiUserApcDispatcher → TThreadedQueue.PopItem
  → mov edx,[eax] with eax=0x3e8 (garbage pointer). I.e. APCProc is executing 
  on a worker against a TThreadDispatchState whose memory has already been 
  freed.
  - Map-decoded faults: worker AV in TObject.Free (freeing a bad ref),
  bus-teardown AV in TThreadedQueue.PopItem (draining a dangling state),
  EInvalidPointer in TObject.FreeInstance (double-free).

  The defect: TThreadDispatchState is freed while an APC still references it — a
  use-after-free / double-free. DetectAndRemoveDeadThreads (which runs eagerly
  on every producer Fire that hits a transient dispatchFailed, constant under
  churn) and Destroy reclaim the "APC reference" based on the APCSignaled flag,
  but that flag is a mutable signal, not a count of outstanding APC refs. When
  dead-thread detection races a concurrently firing/just-fired APC, it releases
  a reference APCProc still owns → premature free → the UAF in APCProc/PopItem
  and the double-free. UnregisterThread doesn't reclaim the APC ref at all and
  relies on SleepEx(0) draining, which the same race defeats.

  This is a deep fix in the library's lock-free reference-counting core — the
  part the 1.01–1.06 history keeps revisiting. Given that, and that I have a
  clean failing repro to drive a TDD fix, I want your call before touching the
  production unit:

● User answered Claude's questions:
  ⎿  · The stress test found a real use-after-free/double-free in 
     GpEventBus.pas's APC ref-counting. How do you want to proceed? → Attempt 
     the library fix
● The user wants the fix. I'm in Phase 4, but the exact interleaving deserves
  one more minimal isolation experiment (Phase 3) to confirm which path does the
  unsound free — my hypothesis is the eager DetectAndRemoveDeadThreads
  reclamation that runs on producer threads during churn. I'll test by
  temporarily neutering it and seeing if the crash disappears (it should turn
  into a leak instead). First, back up the library.

● Bash(cp /x/gp/common/GpEventBus.pas /x/gp/common/GpEventBus.pas.bak && echo
      "backup created" && ls -la /x/gp/common/GpEventBus.pas.bak)
  ⎿  backup created
     -rw-r--r-- 1 gabr 197121 34285 Jun  1 09:33 /x/gp/common/GpEventBus.pa
     s.bak

  Read 1 file (ctrl+o to expand)

● Update(X:\gp\common\GpEventBus.pas)
  ⎿  Added 1 line
      659    state      : TThreadDispatchState;
      660    threadID   : TThreadID;
      661  begin
      662 +  Exit; // EXPERIMENT: neuter eager dead-thread reclamation to
          + isolate the crash                                            
      663    deadThreads := TList<TThreadID>.Create;
      664    try
      665      FLock.BeginRead;

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr >/dev/null 2>&1 && echo "=== run with
      DetectAndRemoveDeadThreads neutered ==="…)
  ⎿  === run with DetectAndRemoveDeadThreads neutered ===
     reproC: producers=True abrupt=0,50 duration=5000ms cap=8
     spawned 563 workers; fired=80504 received=537953; stopping...
     … +5 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Confirmed: with DetectAndRemoveDeadThreads neutered, the crash vanishes (0
  worker faults, clean teardown). So that procedure is doing the unsound free.
  Now the why — and I see it precisely in the code:

  RegisterThread opens the thread handle with DSiOpenThread(THREAD_SET_CONTEXT, 
  …) — enough for QueueUserAPC, but GetExitCodeThread requires
  THREAD_QUERY_INFORMATION. So GetExitCodeThread fails on these handles, and
  DetectAndRemoveDeadThreads takes its else branch — classifying every live 
  thread as dead — then frees their TThreadDispatchStates out from under
  in-flight APCs. It's dormant in normal use (dispatch rarely fails) but lethal
  under churn (firing at just-terminated threads constantly trips
  dispatchFailed).

  Let me restore the library and test that hypothesis by fixing the access mask.

● Bash(cp /x/gp/common/GpEventBus.pas.bak /x/gp/common/GpEventBus.pas && echo
      "restored original"; grep -n "DSiOpenThread\|GetExitCodeThread"
      /x/gp/common/GpEventBus.p…)
  ⎿  restored original
     440:      if not GetExitCodeThread(state.ThreadHandle, exitCode) or (e
     xitCode <> STILL_ACTIVE) then
     … +4 lines (ctrl+o to expand)

● Restored to original 1.06. Now apply the minimal root-cause fix — give the
  thread handle the query right GetExitCodeThread needs:

● Update(X:\gp\common\GpEventBus.pas)
  ⎿  Added 6 lines, removed 1 line
      507        Exit;
      508    finally FLock.EndRead; end;
      509  
      510 -  threadHandle := DSiOpenThread(THREAD_SET_CONTEXT, false, thr
          -eadID);                                                       
      510 +  // THREAD_SET_CONTEXT is required by QueueUserAPC; THREAD_QU
          +ERY_INFORMATION is                                            
      511 +  // required by GetExitCodeThread (used by DetectAndRemoveDea
          +dThreads/Destroy).                                            
      512 +  // Without the query right GetExitCodeThread fails, and dead
          +-thread detection                                             
      513 +  // would misclassify every live thread as dead and free its 
          +state while APCs                                              
      514 +  // are still in flight (use-after-free / double-free under c
          +oncurrent dispatch).                                          
      515 +  threadHandle := DSiOpenThread(THREAD_SET_CONTEXT or THREAD_Q
          +UERY_INFORMATION, false, threadID);                           
      516    if threadHandle = 0 then
      517      raise Exception.CreateFmt('TEventBus.RegisterThread: Faile
           d to open thread handle for thread %d. OS error %d: %s',
      518        [threadID, Winapi.Windows.GetLastError, SysErrorMessage(
           Winapi.Windows.GetLastError)]);

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr >/dev/null 2>&1 && echo "=== fix test: full repro (producers +
      50% abrupt) ===…)
  ⎿  === fix test: full repro (producers + 50% abrupt) ===
     reproC: producers=True abrupt=0,50 duration=5000ms cap=8
     spawned 365 workers; fired=346733 received=2447239; stopping...
     … +5 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Fix verified against the full repro — no crash, clean teardown, dead-thread 
  detection now functions. Let me confirm the noabrupt path too and check for
  leaks (running under cdb so the leak report routes to the debugger instead of
  a blocking dialog).

● Update(reproC.dpr)
  ⎿  Added 1 line
      144    firstFatal  : string;
      145    cap         : integer;
      146  begin
      147 +  ReportMemoryLeaksOnShutdown := True;                        
      148    ParseArgs;
      149    GRandState := GetTickCount or 1;
      150    cap := 8;

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr >/dev/null 2>&1 && echo "built"; echo "=== noabrupt under cdb
      (leak report ->…)
  ⎿  built
     === noabrupt under cdb (leak report -> debugger) ===
     spawned 291 workers; fired=330154 received=2317863; stopping...
     … +2 lines (ctrl+o to expand)
  ⎿  (timeout 1m)

● Bash(grep -iE "memory|block|unexpected|leak|0x|byte" cdb2.out | grep -ivE
      "natvis|symbol|ModLoad|deferred" | head -25; echo "=== now full abrupt
      repro under cdb (lea…)
  ⎿  ntdll!LdrpDoDebuggerBreak+0x2b:
     === now full abrupt repro under cdb (leak check) ===
     spawned 305 workers; fired=376986 received=2724621; stopping...
     … +2 lines (ctrl+o to expand)
  ⎿  (timeout 1m)

● Both variants complete cleanly with no faults and no blocking leak dialog. To
  make the leak check quantitative and rigorous, I'll measure live allocated
  blocks after teardown and compare the churn run against the clean noproducers
  baseline.

● Update(reproC.dpr)
  ⎿  Added 6 lines
      214      FreeAndNil(GProdStop);
      215      FreeAndNil(GBus);
      216    end;
      217 +  var memState: TMemoryManagerState;                          
      218 +  GetMemoryManagerState(memState);                            
      219 +  var liveBlocks := memState.TotalAllocatedMediumBlockCount + 
          +memState.TotalAllocatedLargeBlockCount;                       
      220 +  for var i := Low(memState.SmallBlockTypeStates) to High(memS
          +tate.SmallBlockTypeStates) do                                 
      221 +    liveBlocks := liveBlocks + memState.SmallBlockTypeStates[i
          +].AllocatedBlockCount;                                        
      222 +  Writeln(Format('live allocated blocks after teardown: %d', [
          +liveBlocks]));                                                
      223    Writeln('DONE');
      224  end.

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr >/dev/null 2>&1 && echo built; echo "=== baseline (noproducers)
      ==="; ./reproC…)
  ⎿  === baseline (noproducers) ===
     spawned 734 workers; fired=0 received=0; stopping...
     worker fatal exceptions: 0  first:
     … +6 lines (ctrl+o to expand)
  ⎿  (timeout 40s)

● The measurement line didn't print — something between teardown and the end.
  Let me see full output.

● Bash(./reproC.exe duration=3000 2>&1 | tail -8; echo "EXIT=$?")
  ⎿  reproC: producers=True abrupt=0,50 duration=3000ms cap=8
     spawned 203 workers; fired=338495 received=2387124; stopping...
     worker fatal exceptions: 0  first:
     … +4 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr 2>&1 | tail -2; echo "--- run ---"; ./reproC.exe duration=3000
      2>&1)  ⎿  reproC.dpr(219) Error: E2003 Undeclared identifier: 'TotalAllocatedMed
     iumBlockCount'
     reproC.dpr(219) Error: E2003 Undeclared identifier: 'TotalAllocatedLar
     … +8 lines (ctrl+o to expand)
  ⎿  (timeout 30s)

● Field names were wrong (the dcc32 >/dev/null hid the error, so prior runs used
  the stale-but-fixed exe — which is why they were clean). Correcting the
  TMemoryManagerState field names:

● Update(reproC.dpr)
  ⎿  Added 1 line, removed 1 line
      216    end;
      217    var memState: TMemoryManagerState;
      218    GetMemoryManagerState(memState);
      219 -  var liveBlocks := memState.TotalAllocatedMediumBlockCount + 
          -memState.TotalAllocatedLargeBlockCount;                       
      219 +  var liveBlocks := memState.AllocatedMediumBlockCount + memSt
          +ate.AllocatedLargeBlockCount;                                 
      220    for var i := Low(memState.SmallBlockTypeStates) to High(memS
           tate.SmallBlockTypeStates) do
      221      liveBlocks := liveBlocks + memState.SmallBlockTypeStates[i
           ].AllocatedBlockCount;
      222    Writeln(Format('live allocated blocks after teardown: %d', [
           liveBlocks]));

● Bash("C:\Program Files (x86)\Embarcadero\Studio\37.0\bin\dcc32.exe" -B -U..
      reproC.dpr 2>&1 | grep -iE "error|hint:" | head; echo "=== baseline
      noproducers ==="; ./r…)
  ⎿  === baseline noproducers ===
     live allocated blocks after teardown: 570
     === full producers+abrupt ===
     … +3 lines (ctrl+o to expand)
  ⎿  (timeout 40s)

● Quantitative leak check passes: live blocks after teardown are flat — baseline
  (no firing) 570, full churn+abrupt 574, all-clean 575 — a 4–5 block delta
  (RTL noise), despite creating 200–700 threads and firing millions of events.
  No state/queue/thread accumulation. The fix eliminates both the crash and the
  leak cascade, and dead-thread detection now actually works.

  Let me run a few more iterations to rule out intermittency (the race was
  previously deterministic), then confirm the GUI project still builds.

● Bash(for i in 1 2 3; do echo "--- iteration $i ---"; ./reproC.exe
      duration=3000 2>&1 | grep -iE "fatal|live alloc|viol|invalid|DONE"; done;
      echo; echo "=== rebuild G…)
  ⎿  --- iteration 1 ---
     worker fatal exceptions: 0  first:
     live allocated blocks after teardown: 574
     … +19 lines (ctrl+o to expand)
  ⎿  (timeout 1m)

● Stable across repeated runs (0 faults, flat 574 blocks), and the GUI project
  compiles clean in both configs (only the pre-existing warnings). Root cause 
  fixed and verified.

  Per the project convention (update version history + the .md when modifying a
  source file), I'll record the fix.

● Update(X:\gp\common\GpEventBus.pas)
  ⎿  Added 14 lines, removed 2 lines
       6  ///
       7  ///   Author            : Claude (Anthropic AI), Primoz Gabrije
          lcic
       8  ///   Creation date     : 2026-02-12
       9 -///   Last modification : 2026-05-14                           
      10 -///   Version           : 1.06                                 
       9 +///   Last modification : 2026-06-01                           
      10 +///   Version           : 1.07                                 
      11  ///</para><para>
      12  ///   History:
      13 +///     1.07: 2026-06-01                                       
      14 +///       - Fixed use-after-free / double-free crash under conc
         +urrent Fire +                                                  
      15 +///         rapid RegisterThread/UnregisterThread churn. Regist
         +erThread opened                                                
      16 +///         the subscriber thread handle with THREAD_SET_CONTEX
         +T only (enough                                                 
      17 +///         for QueueUserAPC), but GetExitCodeThread requires  
      18 +///         THREAD_QUERY_INFORMATION. Without it GetExitCodeThr
         +ead always failed,                                             
      19 +///         so DetectAndRemoveDeadThreads (and Destroy) took th
         +e failure branch                                               
      20 +///         and misclassified every *live* registered thread as
         + dead, freeing its                                             
      21 +///         TThreadDispatchState while APCs were still in fligh
         +t. The bug was                                                 
      22 +///         dormant in normal use (dead-thread detection only r
         +uns when a dispatch                                            
      23 +///         fails) but lethal under high thread churn. Fix: ope
         +n the handle with                                              
      24 +///         THREAD_SET_CONTEXT or THREAD_QUERY_INFORMATION.    
      25  ///     1.06: 2026-05-14
      26  ///       - Fixed permanent leak when a subscriber thread termi
          nates without
      27  ///         calling UnregisterThread and without entering alert
          able wait. In

  Read 1 file (ctrl+o to expand)

● Update(X:\gp\common\GpEventBus.md)
  ⎿  Added 2 lines, removed 2 lines
      1  # GpEventBus
      2  
      3 -**Version:** 1.06                                               
      3 +**Version:** 1.07                                               
      4  **Authors:** Claude (Anthropic AI), Primoz Gabrijelcic
      5  **Created:** 2026-02-13
      6 -**Last Modified:** 2026-05-14                                   
      6 +**Last Modified:** 2026-06-01                                   
      7  **License:** Free for personal and commercial use. No rights res
         erved.
      8  
      9  ## Dispatch Order

  Searched for 1 pattern, read 1 file (ctrl+o to expand)

● Update(X:\gp\common\GpEventBus.md)
  ⎿  Added 6 lines
      812  
      813  ## Version History
      814  
      815 +### 1.07 (2026-06-01)                                         
      816 +                                                              
      817 +- Fixed a use-after-free / double-free crash under **concurren
          +t `Fire` + rapid `RegisterThread`/`UnregisterThread` churn** (
          +surfaced by the Stress Test tab's "Thread lifecycle churn" sce
          +nario). `RegisterThread` opened the subscriber thread handle w
          +ith `THREAD_SET_CONTEXT` only — sufficient for `QueueUserAPC`,
          + but `GetExitCodeThread` requires `THREAD_QUERY_INFORMATION`. 
          +With the query right missing, `GetExitCodeThread` always faile
          +d, so `DetectAndRemoveDeadThreads` (and `Destroy`) took the fa
          +ilure branch and **misclassified every live registered thread 
          +as dead**, freeing its `TThreadDispatchState` while APCs were 
          +still in flight.                                              
      818 +- The bug was dormant in normal use because dead-thread detect
          +ion only runs when a dispatch fails (`dispatchFailed`), which 
          +is rare for long-lived subscribers; it became lethal only unde
          +r high thread churn, where firing at just-terminated threads t
          +rips `dispatchFailed` constantly.                             
      819 +- Fix: open the handle with `THREAD_SET_CONTEXT or THREAD_QUER
          +Y_INFORMATION` so `GetExitCodeThread` reports liveness correct
          +ly.                                                           
      820 +                                                              
      821  ### 1.06 (2026-05-14)
      822  
      823  - Fixed permanent memory leak when a subscriber thread termina
           tes without calling `UnregisterThread` and without entering an
            alertable wait. In that case the APC queued by `DispatchToBac
           kgroundThread` is never delivered, so its `AddRef` on the `TTh
           readDispatchState` is never balanced: the state, its `TThreade
           dQueue`, and all captured closures (including any `IGpBuffer` 
           / managed-record fields) persist until process exit.

● Now I'll clean up the purely-diagnostic artifacts (keeping the library fix and
  docs). Let me remove the backup, debugger dumps, and map.

● Bash(rm -f cdb.out cdb2.out cdb3.out reproC.map && rm -f
      /x/gp/common/GpEventBus.pas.bak && rm -f /tmp/pubs.txt && echo "cleaned
      debug artifacts"; echo "remaining re…)
  ⎿  cleaned debug artifacts
     remaining reproC files:
     reproC.dpr
     … +10 lines (ctrl+o to expand)

● Done. Here's the wrap-up.

  Root cause (proven) and fix

  Bug: Use-after-free / double-free of TThreadDispatchState under concurrent
  Fire + thread register/unregister churn.

  Mechanism: RegisterThread opened the subscriber thread handle with
  DSiOpenThread(THREAD_SET_CONTEXT, …). That's enough for QueueUserAPC, but
  GetExitCodeThread needs THREAD_QUERY_INFORMATION. Lacking it,
  GetExitCodeThread always failed, so DetectAndRemoveDeadThreads/Destroy hit
  their failure branch and declared every live registered thread "dead," freeing
  its state while APCs were still in flight. Dormant in normal use (dead-thread
  detection only runs on a failed dispatch); lethal under churn (firing at
  just-terminated threads trips dispatchFailed constantly).

  Fix (GpEventBus.pas:527, one line + comment):
  threadHandle := DSiOpenThread(THREAD_SET_CONTEXT or THREAD_QUERY_INFORMATION,
  false, threadID);

  How it was found and verified (systematic debugging)

  - Reproduced headlessly (tests\reproC.dpr, public API, documented usage) —
  matched the GUI symptoms exactly.
  - Bisected: noproducers clean / noabrupt still crashed ⇒ needs Fire+churn, not
  abrupt termination (so it's a library bug, not misuse).
  - cdb stack + map: AV inside an APC callback (KiUserApcDispatcher → 
  TThreadedQueue.PopItem) on freed memory; double-free in TObject.FreeInstance.
  - Confirmed culprit by neutering DetectAndRemoveDeadThreads (crash vanished),
  then pinpointed the GetExitCodeThread access-right defect.
  - Verified fix: repro clean across repeated runs (0 faults); live-block count
  flat (570 baseline vs 574 churn — no leak despite 200–700 threads / millions
  of events); dead-thread detection now functions; GUI project builds clean in
  DEBUG and release.

  Documentation

  - Bumped GpEventBus.pas and GpEventBus.md to 1.07 (2026-06-01) with a history
  entry describing the fix.

  What I could not verify (needs you)

  I can't drive the GUI. Please re-run scenario C (and A/B/D) in a RELEASE build
  and confirm PASS with no leak dialog on close — that's the authoritative
  check of the original symptom.

  Two notes

  - The fix touches the production library GpEventBus.pas; as its author you may
  want to review the one-liner. No commits were made (per your instruction) —
  the working copy holds the change.
  - tests\reproC.dpr (+ .exe/.drc) remain — it's a solid headless regression 
  test for this exact bug. Want me to keep it (optionally wire it into a build)
  or remove it?

✻ Baked for 22m 42s