Engineering historian

Engineering Historian (v3.1)

Storage is stupid; retrieval is smart — meaning the storage layer stays deliberately dumb (plain markdown, minimal taxonomy) so that intelligence is applied at read and distillation time, not speculated into folder structures. And wisdom is earned through cited evidence, not asserted. This system captures specific decisions as CASES, distills their reasoning into JUDGMENTS, promotes recurring patterns into PRINCIPLES, and hardens checkable principles into STANDARDS. Nothing enters as a rule without a cited case behind it. A principle without provenance is invalid in this system: delete it on sight.

What v3 changes from v2.5: nothing in the pipeline, formats, promotion rules, retrieval, or vault layout. v3 only changes when capture fires. In v2.5 a human had to remember to type /history or /case; that is where the system died in practice. v3 replaces the human trigger with an automatic post-session sweep that drafts cases (status: auto) from the transcript, reviewed in one batch at /distill. Manual /case and /history still work as overrides. Everything below the "Automation layer" heading is the only new material; everything above it is v2.5 verbatim.

What v3.1 changes from v3: nothing in what is captured or how — only the sweep's pre-filter. v3.0 skipped sessions with few user turns, which silently dropped prompt-light agentic sessions (three prompts, hours of autonomous work). v3.1 replaces that significance guess with a triviality gate: skip only when every available deterministic signal — transcript size, user turns, git activity — proves the session trivial; otherwise sweep. When uncertain, capture: a false run costs one cheap NOTHING call, a false skip loses history. Rationale and rejected alternatives: docs/adr/ADR-001-capture-gate-triviality.md; release notes: CHANGELOG.md.

Three modes: capture (Tier 1, now sweep-driven), distillation (Tier 2, periodic), retrieval.

The pipeline

Tier	What it is	Written when	Written by
CASE	A specific problem, the decision made, one-line why	Session end (sweep) or solve time (/case)	Sweep / user
JUDGMENT	Reasoning distilled from a case: rejected alternatives, tradeoffs, tipping factor	Distillation pass	Any competent model, from the record
PRINCIPLE	A general rule; requires 2+ cases across 2+ dates, or 1 case with explicit early-promotion justification	Distillation pass, per promotion rules	Any competent model, mechanically
STANDARD	A principle rewritten as pass/fail checks — no adjectives — enforceable by a less capable model	Distillation pass, only if binarizable	Any competent model, mechanically

The pipeline is a filter, not a conveyor: a case is a legitimate terminal record, and most decisions (tool picks, architecture choices) should live and die as distilled cases — retrievable, never promoted. A case replaced by a later decision gets status superseded (by <case-id>).

Full graduation criteria: references/promotion-rules.md. Read it before running any distillation pass. Entry formats: references/templates.md. Fully populated end-to-end examples: references/worked-examples.md.

Vault location and layout

knowledge/ at the repository root (or, if no repo, at the user's designated vault path — ask once, then remember via a note in knowledge/README.md).

knowledge/
  <project>/
    YYYY-MM-DD.md      # session records; CASE blocks live inside these
  principles.md         # vault-wide: all principles + judgments they cite + declined promotions
  standards.md          # vault-wide: all standards
  retrieval-log.md      # append-only value log
  capture-rules.md      # sweep's binding negative rules + health counters (see Automation layer)
  README.md             # vault path/config notes only
  .sweep/               # sweep machinery (logs, dedup, retry queue, failed/ raw-output archive) — gitignored, never cited

Do NOT create any other folders or files (no events/, playbooks/, judgments/, topic folders). Principles and standards are vault-wide single files because promotion is cross-project by design. If a second session happens the same day for the same project, append under a ## Session 2 (HH:MM) header.

Tier 1 — capture

Capture normally happens automatically at session end via the sweep (see Automation layer), producing cases with status: auto for later review. Two manual paths remain, unchanged:

/case (solve-time override). When a decision is made mid-session (or the user types /case), append a CASE block to today's day file for that project (create a minimal file with frontmatter if none exists yet). The block MUST take under 60 seconds to write:

### CASE: <slug>
status: raw
problem: <one line>
decision: <one line>
why: <one line>
tags: [tag, tag]
promote-early: <justification — ONLY if warranted; omit this line otherwise>

The case ID is <project>/<YYYY-MM-DD>#<slug> — this is how provenance citations work, so slugs must be stable: never rename one after a principle cites it. If the decision has a known horizon at capture time ("pause X until the experiment ends"), add an optional until: line naming the condition — without it, future retrieval may treat a temporary decision as standing. promote-early may only be written at capture time by the capturer; the distiller is forbidden from inventing it later. Do not write more than these few lines. Elaboration is the distiller's job, from the surrounding session record.

Manual /case writes status: raw (human-confirmed at capture); the sweep writes status: auto (awaiting confirmation). That is the only difference between the two capture paths.

/history (manual session capture override). At the end of a session, review the full conversation/session context and write (or complete) knowledge/<project>/YYYY-MM-DD.md. Reconstruct from what actually happened — do not invent. If a section has nothing, write None. The "Cases" section holds CASE blocks in the format above. Any decision worth recording is a case. Full template in references/templates.md. Use this when the sweep didn't fire (a tool with no hook) or the user explicitly asks to capture now.

Section order: What I worked on / Cases / Commands that worked / Problems solved / Mistakes / Prompts worth keeping / Questions I still have / TODOs for next session.

After writing, if the vault is inside a git repository: git add knowledge/ && git commit -m "history: <project> YYYY-MM-DD". Do not push unless the user's normal workflow pushes automatically. Confirm in ONE line (file path + commit hash). No recap — the file is the summary.

Capture rules

• Frontmatter fields are mandatory and exactly as specified.
• Prose over structure inside sections; no tables, no nested bullets beyond one level. (CASE blocks are the one structured exception.)
• Never editorialize about the system itself. Record and stop.
• One file per project per day; multi-project sessions get one file each.
• Commands verbatim and verified, or marked UNVERIFIED.

Tier 2 — distillation pass (/distill)

Run when the user types /distill, asks to "promote", "distill", or "review the vault", or roughly weekly if cases are accumulating. This pass is deliberately mechanical: read references/promotion-rules.md and apply it as written. It must not require frontier judgment — where the rules don't clearly authorize a promotion, the answer is "no promotion", never "use discretion".

Two automation steps run FIRST, before the mechanical procedure — see "Distill: automation steps" under the Automation layer. They are step −1 (coverage/health check) and step 0 (auto-case review). Only after those does the pass below run.

Procedure:

1. Collect all CASE blocks with status: raw across all day files. (Auto cases are NOT collected here — they must be confirmed to raw in step 0 first.)
2. Distill judgments: for each raw case, append a #### JUDGMENT (distilled YYYY-MM-DD) block beneath it (template in references/templates.md), using ONLY the case and its surrounding session record — never invented content. Set case status: distilled. If the record names no rejected alternative, mark the judgment thin: — thin judgments cannot count toward promotion until the user thickens them.
3. Scan for promotions: group distilled cases by shared tipping factor (tags are hints, the tipping factor sentence is the test). Apply promotion rule R3. Draft qualifying principles into principles.md; set contributing cases to status: cited.
4. Attempt standards: for each new or existing unstandardized principle, apply rule R4. If it binarizes cleanly, write it to standards.md; if not, record "not standardizable" with the reason, in the principle entry.
5. Invalidation review: check every status: active principle against (a) its own stated invalidation conditions and (b) direct contradiction by any newly distilled case. On a hit, set status: challenged with the citing case ID — the human resolves to active (with note) or retired. Never delete retired principles; retirement rationale is itself vault content. Also flag any case whose until: horizon has passed — the user confirms superseded, extends the horizon, or drops the line.
6. Log declined promotions in the ## Declined promotions section of principles.md with a one-line reason, so future passes don't re-litigate them.
7. Commit: git commit -m "distill: YYYY-MM-DD". Report to the user in a few lines: coverage/health line (from step −1), N auto cases reviewed (from step 0), N judgments written, promotions made, promotions declined, principles challenged.

Declining is a success mode. Forced generalizations are worse than no principle — the schema exists to keep weak wisdom out.

Retrieval mode

When the user asks about their own past work or rules, search knowledge/ FIRST — before answering from general knowledge — in this order:

1. standards.md — if a standard answers the question, apply/quote it; it's the hardest-tested knowledge in the vault.
2. principles.md — active principles next; mention status if challenged.
3. Day files (grep frontmatter, tags, case slugs, command fragments) — cases and session prose last.

Cite the source and date ("From P-003, provenance seller-engine/2026-06-24: …" or "From stockagent/2026-03-14: …"). When citing a principle, state its evidence weight and scope in the same breath — "P-003: 2 cases, recurrence, domain-scoped" — so its maturity is visible. Confidence is read off provenance (case count, promotion path), never stored or asserted as a field. An auto case is the weakest provenance in the vault — when retrieval surfaces one, say so: "From seller-engine/2026-07-09#<slug> (auto, unreviewed): …". When citing a case that carries an until: horizon, state the horizon and whether it has passed. Retired/challenged principles may be cited only with their status stated; respect scope and does-not-apply boundaries when applying a principle outside its original project. If the vault has no answer, say so explicitly, then answer from general knowledge if possible.

Retrieval log (mandatory)

Every time the vault materially answers a question, append one line to knowledge/retrieval-log.md:

| YYYY-MM-DD | <question, abbreviated> | <source: file or P-/S- ID> | <est. minutes saved> |

Ask the user for the minutes-saved estimate in the same breath as delivering the answer — or estimate it yourself marked (est.). This log remains the falsification instrument for the system: cumulative minutes saved vs. cumulative capture + distillation time. Do not skip it and do not log retrievals that didn't actually help.

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Automation layer (v3 — the only new material)

The automation layer changes WHEN capture happens, never WHAT is captured or how it is promoted. It has three parts: a trigger (a tool hook that fires the sweep), a sweep (a separate prompt file that drafts cases from the transcript), and review (two new steps at the front of /distill). Two support files ship alongside this SKILL rather than inside it, for mechanical reasons: scripts/historian-sweep.sh (a shell script the tool executes from disk — hooks are registered by path, not by SKILL content) and assets/SWEEP.md (a prompt read in a separate headless model call, in a context where this SKILL is not loaded). assets/capture-rules.seed.md is the starting knowledge/capture-rules.md for a new vault. Everything else is here.

The auto status

A CASE with status: auto was drafted by the sweep, not confirmed by a human. Semantics:

• Invisible to promotion. Distillation collects status: raw only; auto ≠ raw. An auto case cannot receive a judgment, count toward a principle, or be cited as provenance until confirmed at step 0.
• Citeable in retrieval, status stated (see Retrieval mode) — it is the weakest provenance in the vault.
• Confirmed to raw at step 0 → it then flows through the pipeline exactly like a manual case.

How the sweep works (conceptually)

At session end (or before a long conversation is compacted), the tool's hook runs historian-sweep.sh. The script first runs the capture gate (v3.1): a deterministic, no-model-call triviality check — any single WORK signal (transcript size, user turns, or git commits in a window) runs the sweep, and skipping requires every available signal to read trivial, so environments exposing fewer signals sweep more, never less. The script then assembles a prompt — SWEEP.md + the current capture-rules.md + today's existing day file + a git delta + the session transcript — and calls whatever model binary is configured (a cheap, distiller-grade model is correct here; sweeps fire often and the work is reconstruction, not frontier reasoning). The model applies the capture test and outputs a complete v3 day file with cases marked status: auto, or the single word NOTHING if the session held nothing worth recording. The script writes the file atomically and commits it. Failures never interrupt the user: they queue in knowledge/.sweep/pending.log for retry at the next /distill.

The capture test the sweep applies (four gates, plus an asymmetry rule that does the calibration a model can't) lives in SWEEP.md so it runs in the sweep's own context. It is summarized here for reference: a segment is captured only if it (G1) resolved into a state change still in force at session end, (G2) had a real alternative present in the record, (G3) is not reconstructible from the surviving code/config alone, and (G4) would cost material time to re-derive. Unsure at G1/G2 → skip (protects provenance); unsure at G3/G4 → capture (only risks noise, which review removes cheaply).

Distill: automation steps (run BEFORE the Tier 2 procedure)

Step −1 — Coverage & pending check (dead-hook guard). Compare git activity against day-file existence: list distinct author-dates of commits since the last distill (git log --since=<last distill date> --format=%ad --date=short | sort -u) and check each against knowledge/<project>/ day files. <last distill date> is the author-date of the most recent distill: commit (git log --grep='^distill:' -1 --format=%ad --date=short); if none exists yet, use the date of the earliest day file in the vault. Open the distill report with one line: Coverage: N/N active days recorded, or WARNING: commits on <dates> with no session record — check the sweep hook. Then process knowledge/.sweep/pending.log: for each entry whose transcript still exists, run historian-sweep.sh --replay <transcript> <cwd> <session-id> (the three tab-separated fields of that pending.log line) — this re-runs the sweep through the same validator/writer/committer as a live hook, bypassing the triviality gate and dedup (a queued entry already earned a sweep), and removes the line from pending.log itself on success; for each whose transcript is gone, report it as a permanent gap (one line) and drop the entry by hand.

Step 0 — Auto-case review. Collect all status: auto cases across day files and present them as ONE batch (slug, problem, decision, why — nothing more). Three verbs per case:

• Confirm → set status: raw. Enters this same distillation pass immediately — one sitting.
• Decline → set status: declined — <one-line reason>. Append the reason to knowledge/capture-rules.md (consolidate with an existing rule rather than adding a near-duplicate). Declined cases remain in the day file as a record; never collected again.
• Edit → amend the wording (usually the why: line), then set status: raw.

After the batch, update the two counters in the ## Sweep health section of capture-rules.md (cumulative confirmed, cumulative declined). Then run the Tier 2 procedure from step 1.

Pre-registered sweep health band (2026-07-07, before first live sweep)

Read from the Sweep health counters at each distill, evaluated once capture-rules.md holds 15+ rules:

• Confirm rate below ~30% sustained → the sweep generates noise faster than the rules teach it. Disable the hook; fall back to manual /history + /case.
• Confirm rate above ~90% sustained → the sweep is too conservative, dropping real cases at G3/G4. Loosen the tie-break toward capture.
• Friction ceiling: if step-0 review routinely exceeds ~5 minutes/week, the layer failed its own hypothesis regardless of confirm rate.
• Displacement signature (success): manual /case usage falling toward zero while confirm rate stays in-band means the sweep replaced memory rather than adding volume.

Migration from v1/v2.5

Existing day files remain valid untouched. On the first /distill, mine old "Decisions made" sections: where an entry is a promotion candidate, append a retroactive CASE block (dated to the original file's date, status: raw) beneath that section rather than rewriting prose. The retrieval log continues unchanged. No files are renamed or moved. A vault created under v2.5 needs only two additions to become a v3 vault: a capture-rules.md (seed provided) and a gitignored .sweep/ — both created automatically on first sweep.

Explicitly out of scope (do not build or suggest)

Vector databases, embeddings, knowledge graphs, dashboards, terminal/build-log ingestion, folder taxonomies beyond the layout above, or any Python tooling. The sweep is a single prompt calling one model; it is not a framework. Additional tool adapters (beyond the Claude Code hook) and any packaging split are deferred until the retrieval log and sweep health band earn them — tooling is earned, not speculated.

Day-60 evaluation — criteria pre-registered 2026-07-07, before first live use

Evaluate against these thresholds, not against impressions:

• Trigger reliability (new in v3): day-file coverage of active git days should approach 100%. This is the core thing the automation exists to fix.
• Sweep confirm rate (new in v3): inside the 30–90% band once capture-rules matures (see health band).
• Capture friction: step-0 review ≤ 5 minutes/week. If manual capture is still relied upon, ask why the sweep didn't catch it.
• Promotion rate: of distilled cases, outside roughly 5–20% promoted → revisit the promotion rules (above: too permissive; near zero despite meaningful work: too strict). Heuristic band, pre-registered as such.
• Retrieval ROI: cumulative minutes saved (retrieval log) vs. cumulative capture + distillation time. Negative → the system is a diary, not a tool. Note: automation makes the vault grow regardless of whether retrieval pays, so this criterion is more load-bearing in v3 than v2.5 — watch it.
• Challenge rate: zero challenged principles by day 60 means the invalidation review isn't being exercised — a healthy vault tests its own rules.

The design is frozen until this evaluation. Improvements after it must cite the log.