feat(distill): close the MemPalace loop — conversations → wiki pages

Add wiki-distill.py as Phase 1a of the maintenance pipeline. This is
the 8th extension memex adds to Karpathy's pattern and the one that
makes the MemPalace integration a real ingest pipeline instead of
just a searchable archive beside the wiki.

## The gap distill closes

The mining layer was extracting Claude Code sessions, classifying
bullets into halls (fact/discovery/preference/advice/event/tooling),
and tagging topics. The URL harvester scanned conversations for cited
links. Hygiene refreshed last_verified on wiki pages referenced in
related: fields. But none of those steps compiled the knowledge
*inside* the conversations themselves into wiki pages. Decisions,
root causes, and patterns stayed in the summaries forever — findable
via qmd but never synthesized into canonical pages.

## What distill does

Narrow today-filter with historical rollup:

  1. Find all summarized conversations dated TODAY
  2. Extract their topics: — this is the "topics of today" set
  3. For each topic in that set, pull ALL summarized conversations
     across history that share that topic (full historical context)
  4. Extract hall_facts + hall_discoveries + hall_advice bullets
     (the high-signal hall types — skips event/preference/tooling)
  5. Send topic group + wiki index.md to claude -p
  6. Model emits JSON actions[]: new_page / update_page / skip
  7. Write each action to staging/<type>/ with distill provenance
     frontmatter (staged_by: wiki-distill, distill_topic,
     distill_source_conversations, compilation_notes)

First-run bootstrap: uses 7-day lookback instead of today-only so
the state file gets seeded reasonably. After that, daily runs stay
narrow.

Self-triggering: dormant topics that resurface in a new conversation
automatically pull in all historical conversations on that topic via
the rollup. Old knowledge gets distilled when it becomes relevant
again without manual intervention.

## Orchestration — distill BEFORE harvest

wiki-maintain.sh now has Phase 1a (distill) + Phase 1b (harvest):

  1a. wiki-distill.py    — conversations → staging (PRIORITY)
  1b. wiki-harvest.py    — URLs → raw/harvested → staging (supplement)
  2.  wiki-hygiene.py    — decay, archive, repair, checks
  3.  qmd reindex

Conversation content drives the page shape; URL harvesting fills
gaps for external references conversations don't cover. New flags:
--distill-only, --no-distill, --distill-first-run.

## Verified on real wiki

Tested end-to-end on the production wiki with 611 summarized
conversations across 14 wings. First-run dry-run found 116 topic
groups worth distilling (+ 3 too-thin). Tested single-topic compile
with --topic zoho-api: the LLM rolled up 2 conversations (34
bullets), synthesized a proper pattern page with "What / Why /
Known Limitations" structure, linked it to existing wiki pages,
and landed it in staging with full distill provenance. LLM
correctly rejected claude-code-statusline (already well-covered
by an existing live page) — so the "skip" path works.

## Code additions

- scripts/wiki-distill.py (new, ~530 lines)
- scripts/wiki_lib.py: HIGH_SIGNAL_HALLS + parse_conversation_halls
  + high_signal_halls + _flatten_bullet helpers
- scripts/wiki-maintain.sh: Phase 1a distill, new flags
- tests/test_wiki_distill.py (21 new tests — hall parsing, rollup,
  state management, CLI smoke tests)
- tests/test_shell_scripts.py: updated phase-name assertion for
  the Phase 1a/1b split

## Docs additions

- README.md: 8th row in extensions table, updated compounding-loop
  diagram, new wiki-distill.py reference in architecture overview
- docs/DESIGN-RATIONALE.md: new section 8 "Closing the MemPalace
  loop" with full mempalace taxonomy mapping
- docs/ARCHITECTURE.md: wiki-distill.py section, updated phase
  order, updated state file table, updated dep graph
- docs/SETUP.md: updated cron comment, first-run distill guidance,
  verify section test count
- .gitignore: note distill-state.json is committed (sync across
  machines), not gitignored
- docs/artifacts/signal-and-noise.html: new "Distill ⬣" top-level
  tab with flow diagram, hall filter table, narrow-today/wide-
  history explanation, staging provenance example

## Tests

192 tests total (+21 new, +1 regression fix), all green in ~1.5s.

docs/DESIGN-RATIONALE.md

@@ -43,10 +43,13 @@ repo preserves all of them:
 
 Karpathy's gist is a concept pitch. He was explicit that he was sharing
 an "idea file" for others to build on, not publishing a working
-implementation. The analysis identified seven places where the core idea
-needs an engineering layer to become practical day-to-day — five have
-first-class answers in memex, and two remain scoped-out trade-offs that
-the architecture cleanly acknowledges.
+implementation. The analysis identified eight places where the core idea
+needs an engineering layer to become practical day-to-day. The first
+seven emerged from the original Signal & Noise review; the eighth
+(conversation distillation) surfaced after building the other layers
+and realizing that the conversations themselves were being mined,
+summarized, indexed, and scanned for URLs — but the knowledge *inside*
+them was never becoming wiki pages.
 
 ### 1. Claim freshness and reversibility
 
@@ -236,6 +239,71 @@ story. If you need any of that, you need a different architecture.
 This is for the personal and small-team case where git + Tailscale is
 the right amount of rigor.
 
+### 8. Closing the MemPalace loop — conversation distillation
+
+**The gap**: The mining pipeline extracts Claude Code sessions into
+transcripts, classifies them by memory type (fact/discovery/preference/
+advice/event/tooling), and tags them with topics. The URL harvester
+scans them for cited links. Hygiene refreshes `last_verified` on any
+wiki page that appears in a conversation's `related:` field. But none
+of those steps actually *compile the knowledge inside the conversations
+themselves into wiki pages.* A decision made in a session, a root cause
+found during debugging, a pattern spotted in review — these stay in the
+conversation summaries (searchable but not synthesized) until a human
+manually writes them up. That's the last piece of the MemPalace model
+that wasn't wired through: **closet content was never becoming the
+source for the wiki proper**.
+
+**How memex extends it**:
+
+- **`wiki-distill.py`** runs as Phase 1a of `wiki-maintain.sh`, before
+  URL harvesting. The ordering is deliberate: conversation content
+  should drive the page, and URL harvesting should only supplement
+  what the conversations are already covering.
+- **Narrow today-filter with historical rollup** — daily runs only
+  look at topics appearing in TODAY's summarized conversations, but
+  for each such topic the script pulls in ALL historical conversations
+  sharing that topic. Processing scope stays small; LLM context stays
+  wide. Old topics that resurface in new sessions automatically
+  trigger a re-distillation of the full history on that topic.
+- **First-run bootstrap** — the very first run uses a 7-day lookback
+  to seed the state. After that, daily runs stay narrow.
+- **High-signal halls only** — distill reads `hall_facts`,
+  `hall_discoveries`, and `hall_advice` bullets. Skips `hall_events`
+  (temporal, not knowledge), `hall_preferences` (user working style),
+  and `hall_tooling` (often low-signal). These are the halls the
+  MemPalace taxonomy treats as "canonical knowledge" vs "context."
+- **claude -p compile step** — each topic group (topic + all matching
+  conversations + their high-signal halls) is sent to `claude -p`
+  with the current wiki index. The model decides whether to create a
+  new page, update an existing one, emit both, or skip (topic not
+  substantive enough or already well-covered).
+- **Staging output with distill provenance** — new/updated pages land
+  in `staging/` with `staged_by: wiki-distill`, `distill_topic`, and
+  `distill_source_conversations` frontmatter fields. Every page traces
+  back to the exact conversations it was distilled from.
+- **State file `.distill-state.json`** tracks processed conversations
+  by content hash and topic set, so re-runs only process what actually
+  changed. A conversation gets re-distilled if its body changes OR if
+  it gains a new topic not seen at previous distill time.
+
+**Why this matters**: Without distillation, the MemPalace integration
+was incomplete — the closet summaries existed, the structural metadata
+existed, qmd could search them, but knowledge discovered during work
+never escaped the conversation archive. You could find "we had a
+debugging session about X last month" but couldn't find "here's the
+canonical page on X that captures what we learned." This extension
+turns the MemPalace layer from a searchable archive into a proper
+**ingest pipeline** for the wiki.
+
+**Residual consideration**: Summarization quality is now load-bearing.
+The distill step trusts the summarizer's classification of bullets
+into halls. If the summarizer puts a debugging dead-end in
+`hall_discoveries`, it may enter the wiki compilation pipeline. The
+`MIN_BULLETS_PER_TOPIC` filter (default 2) and the LLM's own
+substantiveness check (it can choose `skip` with a reason) together
+catch most noise, and the staging review catches the rest.
+
 ---
 
 ## The biggest layer — active upkeep
@@ -255,7 +323,7 @@ thing the human has to think about:
 | Every 2 hours | `wiki-sync.sh full` | Full sync + qmd reindex |
 | Every hour | `mine-conversations.sh --extract-only` | Capture new Claude Code sessions (no LLM) |
 | Daily 2am | `summarize-conversations.py --claude` + index | Classify + summarize (LLM) |
-| Daily 3am | `wiki-maintain.sh` | Harvest + quick hygiene + reindex |
+| Daily 3am | `wiki-maintain.sh` | Distill + harvest + quick hygiene + reindex |
 | Weekly Sun 4am | `wiki-maintain.sh --hygiene-only --full` | LLM-powered duplicate/contradiction/cross-ref detection |
 
 If you disable all of these, you get the same outcome as every