Agent context via nanobot, brain search with ranking, stack memory ask

.gitignore

@@ -64,8 +64,10 @@ impl/
 
 **CLAUDE.md
 **AGENT.md
-# …except the repo's canonical agent guide at the root.
+# …except the repo's canonical agent guide at the root, and the
+# CLAUDE.md that loads it into Claude Code.
 !/AGENT.md
+!/CLAUDE.md
 # Local planning workspace (Nimbalyst) — not product source
 nimbalyst-local/
 

CLAUDE.md

@@ -0,0 +1,3 @@
+@AGENTS.md
+@docs/agent/ops.md
+@docs/agent/dev.md

docs/adr/adr-011-vault-brain-projection.md

@@ -85,3 +85,21 @@ Consequences of the rule:
   trailer on brain commits), and a rebase of the prototype branch onto
   the todo work. Implementation is tracked in
   `docs/todos/brain-projection-plan.md`.
+
+## Update 2026-09-19: search reads the brain
+
+`stack memory search` reads the brain, not the vault. The rule above
+("search and todos read memory") left search blind to generated pages.
+The diary is compiled from the diary room, so its text exists only in
+the brain, and a diary question could not be answered by search. The
+agent fell back to grep on its `vault/` mount, which is the brain.
+
+| Reader | Tree | Reason |
+|---|---|---|
+| `stack memory search` | brain (vault before the first curator run) | brain holds every vault page plus the compiled pages |
+| todos, writes | vault | read-your-writes stays a vault promise |
+
+Cost: a page filed seconds ago is findable after the next mirror tick,
+not at once. Read-your-writes is tested for todos only
+(`tests/integration/test_demo_rig_e2e.py`), so no stated invariant changes.
+

docs/adr/adr-012-nanobot-fork.md

@@ -199,3 +199,16 @@ diff keeps growing.
 * Where the fork lives. Arthur refers to reactivating an existing one; it is
   not visible under `famstack-dev` or `arthware-dev` from this machine.
 * Whether the vault tools move in or stay on the discovery seam.
+
+## Update 2026-09-19
+
+Two shims removed; history size is left to nanobot's own settings.
+
+| Shim | Change | Reason |
+|---|---|---|
+| `lean_state` | removed; `state_log` keeps the debug log, opt-in (`AGENT_STATE_LOG=1`) | duplicated nanobot's microcompact, broke the prefix cache, and its "re-run" placeholders made the model repeat tool calls |
+| `grep_tool` | removed; grep is literal again | ran a regex as a semantic query (lesson 7); the model retried the same grep |
+| `compact_tools` | added; patches `agent.runner._COMPACTABLE_TOOLS` | nanobot's microcompact now also shortens old vault tool results |
+
+`config.json` sets the primary preset's `context_window_tokens` to 32768, so nanobot's token
+consolidation and history snip act at a size that keeps prefill short.

docs/design/agent/agent-improvement-log.md

@@ -1276,3 +1276,40 @@ list_edit(op=add, items=["butter","eggs","flour"]) -> "added 3" in one
 commit (was 3 calls, 3 commits). Full lifecycle correct: every item
 kept, [x] preserved, clean commit trail. Rig now runs the production
 transform, so this exercised the real store code.
+
+## 2026-09-19 - Answer decay removed from lean_state
+
+Failure: in a room with a long history, a vault question ran 11
+iterations, sent the same grep 4 times, then replied with the placeholder
+text `[earlier answer from grep({...}); re-run for the current value]`
+instead of an answer.
+
+Cause: commit 6b80a08 replaced each prior answer of a tool-using turn
+with that placeholder. In a long room most assistant turns in the
+context were placeholders, and the model copied the format.
+
+| Rewrite | Role | Result |
+|---|---|---|
+| prior tool result -> `[prior result of ...]` | tool | kept, not copied |
+| prior tool-turn answer -> `[earlier answer from ...]` | assistant | removed, copied into replies |
+
+Trade-off: a prior answer that recites a list is in the context again.
+The tool result behind it is still a pointer. Regression test:
+`test_no_assistant_message_holds_a_placeholder`.
+
+## 2026-09-19 - Context size left to nanobot
+
+The shims that rewrote context worked against nanobot's own mechanisms.
+
+| Item | Before | After |
+|---|---|---|
+| Prior tool results | `lean_state` placeholder, all of them, every turn | nanobot microcompact: 10 newest kept, older >= 500 chars omitted |
+| Vault tool results | not compactable (names missing from `_COMPACTABLE_TOOLS`) | compactable (`compact_tools.py`) |
+| Vault grep | semantic query via `grep_tool` | literal grep |
+| `context_window_tokens` | 200000 (default; consolidation never ran) | 32768 (budget 23.5k, consolidation target 11.7k) |
+| `llm-state.log` | every `build_messages` call | only with `AGENT_STATE_LOG=1` |
+
+Why autocompact did not shrink the room: it keeps the last 8 messages,
+extended back to the start of that turn. A turn with 11 tool calls has
+24 messages, so the whole turn stayed.
+