Borrowing it
Nothing to install: this file belongs to richardthe3rd/cambridge-beer-festival-app. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/richardthe3rd/cambridge-beer-festival-app/main/.claude/skills/failure-archaeology/SKILL.mdgit clone --depth 1 https://github.com/richardthe3rd/cambridge-beer-festival-appWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/failure-archaeology)<a href="https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/failure-archaeology"><img src="https://agentmods.dev/badge/skills/richardthe3rd/cambridge-beer-festival-app/failure-archaeology/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/richardthe3rd/cambridge-beer-festival-app/failure-archaeology"><img src="https://agentmods.dev/badge/skills/richardthe3rd/cambridge-beer-festival-app/failure-archaeology.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00214 | $0.11058 |
| Opus 5.5 | $0.00086 | $0.04423 |
| Sonnet 5.5 | $0.00043 | $0.02212 |
| Haiku 4.5 | $0.00021 | $0.01106 |
Grade A, and why
failure-archaeology scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 749 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Failure Archaeology
This is the chronicle. Every row below is a closed (or explicitly still-open) investigation: what broke, why, the evidence trail (issue/PR/SHA/file:line), its final status, and the one-sentence lesson to carry forward. It exists so an agent with zero context doesn't spend a review cycle re-proposing a fix that was already tried and rejected, or re-breaking something that was already hardened.
Entry format (strict): Symptom → Root cause → Evidence → Status → Lesson.
Status vocabulary:
fixed-in— landed, cite the PR/SHA/commit message.rejected-because— proposed, explicitly turned down, with the reason.still-open— known, not yet fixed; check before assuming it's new.
All PR/issue numbers and SHAs below were checked against git log and the working
tree on 2026-07-02. The local clone is shallow (~50 commits) — anything with a
SHA was verified directly; older items are cited by PR/issue number only (correct
per GitHub, not re-derivable from git log here).
1. State management (BeerProvider & domain controllers)
Rapid festival switch races the drinks fetch
- Symptom → switching festivals quickly showed the previous festival's
drinks; a slow in-flight
loadDrinks()overwrote the newer festival's data. - Root cause → concurrent
loadDrinks()calls, no cancellation token; the older completion clobbered newer state. - Evidence → PR #263 (discard stale drinks responses); PR #275 added the
_drinksLoadTokenguard (Fixes #266). Guard checked atlib/providers/beer_provider.dart:480,495,519today (_refreshDrinksFromNetwork). - Status → fixed-in #275, still enforced.
- Lesson → any async load keyed to a mutable "current selection" needs a
monotonic token;
awaitalone cannot cancel an orphaned future.
_currentFestival reference goes stale after a background registry refresh
- Symptom → a server-side change to a festival's
availableBeverageTypes(e.g. cider added) silently never loaded for the session. - Root cause →
initialize()seeds_currentFestivalfrom cache, firesunawaited(loadFestivals()); the success branch only reassigned_currentFestivalwhen it was null, so the stale cachedFestivalobject stayed referenced while in-flightloadDrinksused its old types. - Evidence → issue #306 (priority:high); fixed by PR #362.
- Status → fixed-in #362.
- Lesson → when a background refresh replaces a collection, re-resolve any held reference into the new collection by domain key, not identity.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2mo ago First seen · 749 lines · 214 tokens per session scan A 28649f5ebaa5
failure-archaeology is a skill published in the GitHub repository richardthe3rd/cambridge-beer-festival-app (3 stars, last pushed today), licensed MIT. It adds 214 tokens to every session and 11,058 once invoked, about $0.0009 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
failure-archaeology compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| failure-archaeologyrichardthe3rd/cambridge-beer-festival-app | Skill | 3 | today | MIT | A | 214 | Claude Code |
| systematic-debuggingopen-metadata/OpenMetadata | Skill | 16k | yesterday | Apache-2.0 | A | 37 | Claude Code |
| log-error-digestzebbern/claude-code-guide | Skill | 4.7k | 3d ago | MIT | A | 71 | Claude Code, Codex |
| cwv-optimizeradobe/skills | Skill | 319 | yesterday | Apache-2.0 | A | 112 | Claude Code |
| ci-fixersipyourdrink-ltd/bernstein | Skill | 1.2k | yesterday | Apache-2.0 | A | 15 | Claude Code, Codex |
| triaging-web-analytics-supportPostHog/posthog | Skill | 41k | yesterday | none | A | 151 | Claude Code, Codex |
| diagnosing-missing-recordingsPostHog/posthog | Skill | 41k | yesterday | none | A | 76 | Claude Code, Codex |