Compound Engineering's Compounding Knowledge Lifecycle

Key takeaways

1. Compound engineering's founding bet. "each unit of work should make the next unit easier." Code improves the product, not the process; what compounds is knowledge — every solved problem, named concept, and documented convention in a form retrievable at the exact moment future work needs it.
2. The real bottleneck = retrieval. , not writing. Postmortems "rot in wikis because nobody re-reads them." This system closes the loop by making retrieval automatic across 5 skills, not a matter of voluntary discipline.
3. A learning (solution doc). = 1 markdown file = 1 solved problem, under docs/solutions/<category>/. The entire frontmatter serves search, not narrative: title (grep target #1), tags (synonym surface — grep tags:.*(menu|routing|handoff) without opening a file), module/component ("is this my area?"), problem_type (the routing switch), applies_when (a 3-line self-selection test), severity (ranking when several match), date (obsolescence signal).
4. problem_type = 2 tracks. bug-track (what broke: runtime_error, test_failure, performance_issue, security_issue…) and knowledge-track (what was decided/discovered: architecture_pattern, design_pattern, tooling_decision, convention, workflow_issue, best_practice…). "A system that only retains bugs forgets the essential part of what a team learns." Living census: 35 learnings, 6 categories, skill-design in the lead (20).
5. Pattern doc. = one notch up: generalized from several learnings → more leverage, more risk if it goes stale. None promoted here yet (docs/solutions/patterns/critical-patterns.md = a slot waiting to be filled).
6. Capture = /ce-compound. , core discipline = timing: document while context is still fresh (same session as the fix, while the failed attempts and the "ah, THAT's why" are still there). A week later → it degrades into a summary.
7. Mechanics. fan-out of subagents (context analyzer = category/name/frontmatter, solution extractor = prose body problem/investigation/solution/prevention, related-docs finder = dedup check); only the orchestrator writes ONE doc, subagents never touch tracked files. Other entry points: /ce-debug (offers a compound after root-cause), /ce-pov ("compound it" → tooling_decision in headless mode), lightweight mode (small lessons, skips the dedup check).
8. "The life of a learning". (canonical example): issue #714 (the agent stops after the menu) → root cause (per-option routing in a reference file that wasn't loaded) → fix + /ce-compound → learning post-menu-routing-belongs-inline.md → regression test + doctrine in AGENTS.md ("Inline the Trigger, Not the Content"). One incident, 4 durable artifacts. "Compounding" = failure classes get retired, not just documents piling up.
9. Memory map, axis = durability. DURABLE (git): docs/solutions/ (the 35 learnings), CONCEPTS.md (vocabulary/glossary, never specs), STRATEGY.md (direction/tracks), docs/plans/ + brainstorms/ (the WHY). EPHEMERAL (derived): repo-profile cache (re-derived 1×/commit, shared by 9 skills, never a source of truth — deleting it loses nothing). Rule: knowledge you'd mourn → git; re-derivable → /tmp. Plans are never edited after execution → they still explain the why months later.
10. Detection: nothing pushes knowledge toward you. (no digest, no "read the wiki"). 5 skills pull it at decision time, via a shared learnings-researcher protocol, grep-first (memory is designed to be searched without being read). Funnel: 35 docs → parallel frontmatter greps → a handful of candidates (~30-line frontmatter) → full-read of the winners → 5 distilled findings into the caller's context.
11. Consumers. /ce-plan (learnings → constraints & KTDs), /ce-brainstorm (frames the scope), /ce-code-review (always-on reviewer: followed / violated verdict against the actual diff — "the sharpest tooth"; a violation = a file:line finding, not a suggestion), /ce-ideate (prunes past dead ends), /ce-debug (surfaces known root causes).
12. 2 trust rules. (1) Present evidence wins — if a learning contradicts the current code, the conflict is flagged instead of failing it (a confidently wrong memory is worse than none); (2) Date is signal — every learning carries its date to weigh whether the world has moved on.
13. Refresh — "memory that only ever grows eventually lies.". 3 counterforces at different tempos: read time (present evidence wins, free); write time (when adding/editing a CONCEPTS.md entry, inspect its coherence neighborhood — the referenced sibling terms — and correct drift for which there is evidence; bounded, never a full audit run on a hunch); on demand (/ce-compound-refresh, a deliberate sweep, NOT a default follow-up, only runs when there is a reason, takes a scope hint — /ce-compound-refresh payments — because a full-corpus refresh is almost never the right spend).
14. The complete loop via /ce-explain. (skill shipped "yesterday," everything actually happened): brainstorm pulls the repo-profile from cache; planning surfaces 5 learnings (3 must-apply: inline menu routing [legacy of #714], $ARGUMENTS portability, SKILL_DIR anchor); implementation creates its mirrored regression test; review audits the diff against 8 learnings (all followed) and rejects a reviewer-proposed fix that would have reintroduced the original failure mode ("memory didn't just inform the work, it defended it"); compound vocabulary (Explainer, Check-in → CONCEPTS.md); leftover → issue #1057 → future learning #36. "No step required anyone to remember to consult the memory."
15. Why it compounds (financial metaphor). learning = principal, every retrieval that changes a decision = interest payment, pattern doc = reinvestment. Failure modes avoided: wiki rot, stale guidance that kills new work, uncurated accumulation, invisible memory, decay, silos (a single docs/solutions/ serves 9 skills).
16. Direct link to this repo. the docs/solutions/ convention (frontmatter module/tags/problem_type) documented in the veille repo's CLAUDE.md is exactly this system; the compound-engineering:* skills (ce-compound, ce-plan, ce-code-review, ce-compound-refresh…) are installed here. A natural candidate for firm-wide promotion (a capitalization pattern).