Night Market Failure Archaeology

This is a reference document, not a runbook. It records every major investigation, dead end, rejected fix, and revert in this repo as symptom, root cause, evidence, status, and lesson, so nobody re-fights a settled battle. For triage of a failure happening right now, use night-market-debugging-playbook. Come here when a proposed change smells like something the repo already tried and rejected.

Jargon used below:

• "py39 hooks": hook scripts run under the host system Python (3.9 floor), while the rest of the repo requires Python 3.12. Enforced by .github/workflows/python39-compat.yml.
• "unbloat": the conserve plugin's dead-code deletion campaign.
• "Stop hook": a Claude Code hook that runs when a session turn ends.
• "settled": the fight is over. Re-opening it requires new evidence and a note in the collective memory, not a hunch.

How to use this chronicle

1. Before implementing, scan the battle titles and the recurring-class table for anything resembling your plan.
2. If a battle matches, read its lesson. Follow it, or write down why this time is different before overriding it.
3. Verify any hash you rely on: git log --format='%h %s' -1 <hash>.
4. When your own battle settles, add an entry (format at the bottom).

Settled battles

SB1: tasks_manager cross-plugin DRY consolidation (reverted)

• Symptom: three near-identical tasks_manager.py copies in attune, sanctum, and spec-kit looked like textbook duplication.
• Root cause of the failure: consolidating them into a root scripts/tasks_manager.py (1,169 lines deleted across 6 files) broke plugin self-containment. Plugins are independent deployables that run from a Claude Code cache directory, so they cannot import from the repo root.
• Evidence: 054e2679 (consolidate, 2026-01-23), 29961cd2 (revert, same day), d89a55c7 (differentiated per-plugin copies). All three copies exist today under plugins/<p>/scripts/tasks_manager.py. docs/dependency-audit.md tracks cross-plugin deps and fallbacks.
• Status: settled. Per-plugin copies are intentional.
• Lesson: DRY across plugin boundaries is an anti-pattern here. Do not "helpfully" re-consolidate duplicated plugin scripts.

SB2: LSP proxy (speculative infrastructure, killed)

• Symptom: scripts/lsp-proxy.py added for "graceful server fallback" with no consumer demanding it.
• Root cause: speculative abstraction built ahead of need.
• Evidence: 2fcb256d (add), killed in PR #193 review, bc318947 (revert, 2026-02-11, restores .cclsp.json).
• Status: settled. Do not re-add without a concrete consumer.
• Lesson: infrastructure without a present consumer dies in review. See also .claude/rules/shared-utility-consumer-rule.md.

SB3: Tier-3 unbloat over-deletion (2026-03-28, the big one)

• Symptom: unbloat deleted 182 files (66K lines) using only the Python import graph to decide what was dead.
• Root cause: skills and commands reference scripts from markdown, not Python imports. 28 actively referenced scripts plus 18 companion test files were classified dead and deleted.
• Evidence: a3f11323 (the deletion), 3f280334 (restore the 28 scripts and 18 tests), b5f08bf7 (CI repair: dead docs workflow, missing capabilities entries), d6c128f5 and 01a13e70 (further repair and governance follow-ups). Recovery point was branch backup/unbloat-20260328.
• Status: settled, with the highest single blast radius on record.
• Lesson: any deletion campaign must scan markdown references (skills, commands, agents), never imports alone. Always take a backup/unbloat-<date> branch first.

SB4: bulk lint ignores (reverted)

• Symptom: global ruff ignores made parseltongue lint pass while hiding 73 real violations.
• Root cause: silencing the gate instead of fixing the findings.
• Evidence: 06b9b1db (2026-03-10) reverts the bulk ignores and fixes all 73 at source. The commit body cites issue #296 as the anti-bulk-ignore policy anchor.
• Status: settled. Constitution rule 6 also bans bare suppressions.
• Lesson: a suppressed violation is a hidden defect. Fix at source or suppress per line with a stated reason.

SB5: datetime.UTC breaking py39 hooks (fixed 3+ times)

• Symptom: hook import chains crash under host Python 3.9 because datetime.UTC is a 3.11+ alias. On PR #511 this was the sole failing check, with three cascade failures rooted in one ImportError.
• Root cause: ruff's pyupgrade rule UP017 kept auto-rewriting timezone.utc back to datetime.UTC, silently re-breaking the fix. The linter was fighting the fix.
• Evidence: 18c9340d (leyline quota_tracker, 2026-05-07), b0049fde (abstract), 709dafc9 (attune).
• Status: settled by a durable guard, not by the fixes themselves: an AST-scanning test (plugins/leyline/tests/test_python39_compat.py) fails CI on any reintroduction, root ruff config extend-ignores UP017, and the surviving per-line pyupgrade suppression markers each carry a stated reason.
• Lesson: when the linter fights the fix, only an AST invariant test holds the line. A fix commit alone will be reverted by tooling.

SB6: unguarded yaml/anthropic imports in hook chains

• Symptom: every git commit emitted a PreToolUse hook ModuleNotFoundError.
• Root cause: gauntlet's __init__ eagerly imported dependencies (yaml, anthropic) that the bare host interpreter running hooks does not have.
• Evidence: 45dd77ef (guard yaml import, #518, 2026-05-08), 9bfc0a7a (defer anthropic import to function scope). Regression tests block re-imports with a sys.meta_path blocker (plugins/gauntlet/tests/unit/test_challenges.py).
• Status: settled.
• Lesson: hook entrypoints and everything they transitively import must be import-safe under a bare interpreter with no third-party packages.

SB7: herald LLM timeout exceeding the hook budget

• Symptom: the herald double-shot-latte Stop-hook judge produced no verdict at all in the failure case.
• Root cause: LLM_TIMEOUT_SECONDS = 30 inside a hook registered with a 10-second budget. The harness killed the whole hook before the LLM subprocess returned, so even the deterministic path's verdict was lost.
• Evidence: 3d22f02a (the judge), 268cff89 (2026-05-30: cap LLM timeout to 8s, gate the LLM second shot to the single ambiguous outcome). A guard test asserts LLM_TIMEOUT_SECONDS is below the registered hook timeout (plugins/herald/tests/unit/test_double_shot_latte.py).
• Status: settled.
• Lesson: assert every subprocess timeout against the registered hook budget in a test. Deterministic tests do not exercise optional branches, so the optional branch needs its own guard.

SB8: silent scanner failures B1-B4

• Symptom: quality scanners silently dropped files on malformed input, so broken inputs produced clean-looking reports. One metric reported Elite on malformed tags.
• Root cause: except-and-continue blocks in scanner loops swallowed parse errors.
• Evidence: 666171c3 (2026-06-18, fixes #575, findings B1-B4 from PR #521), b6de71cf (plugin-check: bound hangs, unmask failures).
• Status: settled. Scanners now emit ADVISORY findings instead of skipping silently.
• Lesson: except-continue in a scanner is a landmine. A scanner that cannot parse an input must say so in its output.

SB9: hooks reading env vars Claude Code never sets

• Symptom: the [Learning] discussion digest went quiet after 2026-04-25. That starvation was the only visible symptom.
• Root cause: PreToolUse/PostToolUse hooks (skill_execution_logger, pre_skill_execution, homeostatic_monitor in abstract, leyline noqa_guard, sanctum deferred_item_watcher) read CLAUDE_TOOL_* environment variables that Claude Code never populates. The payload arrives as JSON on stdin. The hooks exited 0 without doing anything, for months.
• Evidence: CHANGELOG 1.9.14 (2026-06-27). Fix: canonical stdin-first reader read_hook_payload in plugins/abstract/hooks/shared/hook_io.py, with env-var fallback for the test harness. Consumers: the five hooks above.
• Status: settled.
• Lesson: a hook that exits 0 is not a hook that worked. Verify hooks actually fire and consume the real payload contract (stdin JSON).

SB10: neutered mypy gate

• Symptom: typecheck was green while real type errors accumulated.
• Root cause: the global mirrors-mypy pre-commit hook silently disabled 13 error codes, and the typecheck hook ran --changed instead of --all.
• Evidence: CHANGELOG 1.9.12 (2026-06-18): neutered hook removed, per-plugin strict mypy with --all, new typecheck.yml workflow gating every PR.
• Status: settled.
• Lesson: a green gate that disables checks is worse than no gate. Audit what a gate actually runs, not whether it passes.

SB11: CI pin breakage (recurring)

• Symptom: CI failures from tool pins that were never valid or aged out.
• Root cause: setup-uv@v8 bare tag does not exist upstream, and bandit newer than 1.8.6 dropped Python 3.9 support needed by hooks.
• Evidence: f81d89a5 (pin setup-uv to v8.2.0), 25bf5a9d (pin bandit 1.8.6).
• Status: settled by standing guards scripts/check_pinned_versions.py and scripts/check_ruff_version.py (pre-commit, run only when the relevant files are staged).
• Lesson: pin exact tags and let the guard scripts flag drift. Never trust a major-version alias tag to exist.

SB12: gh discussion CLI does not exist

• Symptom: playbooks called gh discussion create/comment/list and failed. There is no such gh subcommand.
• Root cause: hallucinated CLI surface. GitHub Discussions are reachable only through the GraphQL API.
• Evidence: CHANGELOG (minister playbook repair replaced the calls with GraphQL mutations). Working templates live in plugins/leyline/skills/git-platform/modules/command-mapping.md using gh api graphql.
• Status: settled.
• Lesson: Discussions equal GraphQL only. Any script touching Discussions goes through gh api graphql, never a gh discussion subcommand.

SB13: pensive break halted multi-hit overflow detection

• Symptom: pensive's integer-overflow scan reported at most one hit per file (PEN-013).
• Root cause: a loop break after the first finding.
• Evidence: 4993273b (2026-06-22).
• Status: settled.
• Lesson: in detection loops, collect all findings. An early exit in a scanner is a correctness bug, not an optimization.

SB14: broken relative paths from the plugin cache directory

• Symptom: conserve's session-start hook failed when the plugin ran from the Claude Code cache directory instead of the repo checkout.
• Root cause: a relative path assumed the repo layout. Installed plugins execute from a cache dir where sibling repo paths do not exist.
• Evidence: CHANGELOG ("Inlined JSON utilities in conserve session-start hook"), later generalized in a8c9e4e9 (vendor json_utils.sh per plugin).
• Status: settled.
• Lesson: plugins run from a cache dir. No relative paths out of the plugin root, ever. Vendor small utilities per plugin (see SB1: this duplication is intentional).

SB15: imbue body-text fallback over-classification

• Symptom: imbue classified unrelated skills as review-workflow because a fallback matched loose body text when frontmatter did not answer.
• Root cause: a defensive fallback standing in for data that should be authoritative. The fallback masked the real signal instead of failing loudly.
• Evidence: 69fbd32c (2026-06-24, remove the fallback). Pattern codified in .claude/rules/prefer-invariants-over-fallbacks.md (9f771794) and the imbue verifier-integrity module (29081fda).
• Status: settled.
• Lesson: a fallback that guesses is worse than a loud miss. Prefer invariants over fallbacks.

Recurring failure classes (ranked)

Ranked by observed cost across the repo's history. Hashes are sample evidence, not complete lists.

Rank	Class	Shape	Sample evidence	Standing guard
RC1	Silent failure / swallowed exceptions	except-continue, exit 0 on failure, dropped files	e0d1c464, 10b4b790, 52ae1459, fedb1c5b, 0d28a260, bfebb1ad, 7987649c, 89faaaf7	Constitution rule 10 and the narrow-bare-except campaign
RC2	py39 / host-Python import fragility	hooks crash under system Python	SB5, SB6 hashes	python39-compat.yml, AST test, meta_path tests
RC3	PR-review rework churn	long fix-chains after review	tautological tests a94240e2, f1cbbcf1, 30e58586, 42f7ce84; AI-slop prose 2a039760, 62f598e9; stale wiring 204b927c, 332bcb75	shift-left pre-commit guards, slop-check CI
RC4	Unbloat over-deletion	import-graph-only deletion	SB3 hashes	markdown-reference scan, backup branches
RC5	CI pin breakage	invalid or stale tool pins	SB11 hashes	check_pinned_versions.py, check_ruff_version.py
RC6	Version drift	manifests and SKILL.md frontmatter out of lockstep	fan-out via plugins/sanctum/scripts/update_versions.py	sanctum:version-updates flow
RC7	Fallback over-classification	guessing fallback masks bad data	SB15 hashes	prefer-invariants-over-fallbacks rule

Dead ends: fenced off

These branches are superseded. Do not resume work on them. They stay for archaeology only.

Branch	Why it is dead
attune-tasks-poc	Superseded. Its lineage spawned the reverted SB1 consolidation.
agent-coordination	2026-03-17 experiment, superseded by conjure and egregore.
feature/knowledge-brain	Pre-1.0 prototype, superseded by memory-palace.
feat/slop-clean-before-post	Superseded by scribe Tier-5 patterns on master (509bffaf).

The backup/unbloat-* branches (a dozen as of 2026-07-02) are recovery snapshots and the institutional memory of RC4. backup/unbloat-20260328 was the recovery point for SB3. Do not delete them casually.

The costliest three (judgment call)

1. The PR-review rework loop (RC3). Roughly 140 fix-chain commits spent repairing review findings after the fact (estimate from the 2026-07 repo audit, exact count unverified). Response: shift quality left into pre-commit guards so review stops being the first gate.
2. The 2026-03-28 unbloat cascade (SB3). Highest single blast radius: one commit, 182 files, multi-commit recovery, CI repair.
3. py39 hook fragility (SB5, SB6). Each occurrence was a total hook outage, and the linter actively fought the fix until an AST invariant test ended it.

Adding an entry when a new battle settles

What counts as a settled battle:

• a revert of a merged change (with the reason understood)
• a bug fixed more than once before a durable guard landed
• a feature or abstraction killed in review or post-merge
• an incident with a multi-commit repair chain

Format: copy the SB block shape. Five fields, all required: Symptom, Root cause, Evidence (commit hashes, each verified with git log --format='%h %s' -1 <hash> before you write it down), Status, Lesson. Assign the next SB number. Add the class to the RC table if it recurs.

Where the lesson must also land (this file is not the system of record for policy):

• GitHub Discussions [Learning] or [PR Finding] post, and the decision journal (docs/tradeoffs.md, docs/lessons-learned.md, append-only). See night-market-collective-memory.
• If the lesson is a durable behavioral policy, graduate it to .claude/rules/ through the pipeline in night-market-research-methodology, subject to night-market-change-control.

When NOT to use

• A failure is happening right now and you need triage steps: use night-market-debugging-playbook.
• You need the release/test/lint command anatomy behind a fix: use night-market-operations.
• You are deciding how to classify or gate a change: use night-market-change-control.
• You want the design invariants these battles produced (plugin self-containment, hook import-safety): use night-market-architecture-contract.
• You are recording a decision or lesson into Discussions or the decision journal: use night-market-collective-memory.

Exit Criteria

• Every commit hash cited in this file resolves: the loop in Provenance below prints no MISSING lines.
• For the change at hand, the matching SB/RC entries were read, and any override of a lesson is written down with a rationale.
• Any newly added entry has all five fields and at least one verified commit hash.
• The new entry's lesson is cross-posted per the collective-memory skill (Discussions post or decision-journal line exists).

Provenance and maintenance

Compiled 2026-07-02 against repo v1.9.15, branch master history (1,247 commits). Volatile facts: branch list, RC ranking, and the costliest-three judgment reflect the repo as of that date. The ~140 fix-chain commit count for RC3 is an unverified estimate.

Re-verification commands:

# All cited hashes still resolve
for h in 054e2679 29961cd2 d89a55c7 2fcb256d bc318947 a3f11323 \
  3f280334 b5f08bf7 d6c128f5 01a13e70 06b9b1db 18c9340d b0049fde \
  709dafc9 45dd77ef 9bfc0a7a 3d22f02a 268cff89 666171c3 b6de71cf \
  f81d89a5 25bf5a9d 4993273b a8c9e4e9 69fbd32c 9f771794 29081fda \
  509bffaf e0d1c464 10b4b790 52ae1459 fedb1c5b 0d28a260 bfebb1ad \
  7987649c 89faaaf7 a94240e2 f1cbbcf1 30e58586 42f7ce84 2a039760 \
  62f598e9 204b927c 332bcb75; do
  git log --format=%h -1 "$h" >/dev/null 2>&1 || echo "MISSING $h"
done

# Dead-end and backup branches still present
git branch --list 'backup/unbloat-*' attune-tasks-poc \
  agent-coordination 'feature/knowledge-brain' \
  'feat/slop-clean-before-post'

# Standing guards still in place
ls plugins/leyline/tests/test_python39_compat.py \
  plugins/abstract/hooks/shared/hook_io.py \
  scripts/check_pinned_versions.py scripts/check_ruff_version.py
rg -q "meta_path" plugins/gauntlet/tests/unit/test_challenges.py
rg -q "LLM_TIMEOUT_SECONDS < hook_timeout" \
  plugins/herald/tests/unit/test_double_shot_latte.py