[yeroo]

CLAUDE.md was 178,494 characters, over Claude Code's 150,000-character limit for a memory file, so part of the project's instructions could miss the agents. It now keeps only what every session needs (14,838 characters), and the per-feature notes live in area files under docs/claude/.

Closes #1903

What changed

• CLAUDE.md: the rule at the top (a feature's notes go into its area file, never a new section here; 40,000-character budget; CI check), then How work is done, an Area notes index (one bullet per area file: when to read it, the topics and issue numbers, so a grep for an issue number lands on the right file), a short Build and test (only commands from ci.yml), Cross-crate invariants (restated from the area notes, each naming its file), and the kept sections verbatim: DOCX Bidi Rendering, Text input (dead keys, IME), Build info, Dialogs and typed input (Tests: type into every editable input (all dialog fields, formula bar, Name Box, Find, ribbon combos, Backstage fields) with real keys; a catalogue so none is missed #1029).
• docs/claude/: 21 area files holding the other 74 sections, moved verbatim by script in their original order: docx-editing, suite-document, pdf-export, html-import, clipboard, macos, suite-shell, suite-extensions, ribbon, help, ui-plugins, project-formats, project-text-styles, project-gantt, project-table, project-task-info, project-scheduling, sheet-ui, sheet-file, terminal-editors, mail. Each opens with a header saying what it covers, that it is not loaded automatically, and that paths are from the repository root.
• scripts/check-claude-md.py (stdlib only) fails when CLAUDE.md exceeds 40,000 characters, an area file has no bullet of its own in the Area notes index, CLAUDE.md names an area file that does not exist, a ## heading appears twice across the files, or CLAUDE.md has a ## section not in its KEPT list. That last check stops a branch written against the old CLAUDE.md from adding a feature section back. --moved-from [REV] (default: the merge base with origin/main) proves the move.
• CI: the test job runs the check right after checkout (Linux leg). The new unit tests run in the sweeps' existing unittest discover -s scripts step.

The one edit inside moved text: #1374's "(#1378, below)" is now "(#1378, above)" (it already was above in the old file). Other "below"/"under" references stay in the same file, in order.

Tests

• python3 -m unittest discover -s scripts -p 'test_check_claude_md.py' -v: 22 tests OK (budget in characters, not bytes; padded file fails; unindexed, cross-pointer-only and missing area files; duplicate headings; fenced code; KEPT; --moved-from cases). The whole scripts set: 69 tests OK.
• python3 scripts/check-claude-md.py → CLAUDE.md: 14838 / 40000 characters, 21 area files in docs/claude/; on the old CLAUDE.md it fails (budget, 74 unlisted sections, missing kept sections).
• python3 scripts/check-claude-md.py --moved-from (merge base):

CLAUDE.md: 14838 / 40000 characters, 21 area files in docs/claude/
--moved-from 7e4e9a9590be9b3b49c27425b67b77621b97d2e0: 79 old sections
new       ## Area notes
new       ## Build and test
new       ## Cross-crate invariants
79 of 79 old sections found exactly once; 1 body diff(s)
--- CLAUDE.md (old): ## yppxy terminal prompt edits at a caret (#1374)
+++ docs/claude/terminal-editors.md: ## yppxy terminal prompt edits at a caret (#1374)
@@ -8,5 +8,5 @@
   commits the whole text wherever the caret is. The edits clamp the caret, as
   tests assign `buf` directly. The drawn `▏` sits at the caret and `field-read
   yppxy-prompt` reports it. Ctrl+A selects the buffer (#1376; typing and the
-  edit keys replace or collapse it). Copy/paste is there (#1378, below);
+  edit keys replace or collapse it). Copy/paste is there (#1378, above);
   click-to-place is not; Backstage Save As's name field is separate.

No Rust is touched.

Review

• Plan agreed at v2 after one critique round (added the KEPT allowlist, Cross-crate invariants, kept the dialogs section, --moved-from against the merge base).
• revmux round 1 (claude-only, 4 reviewers, none degraded): 2 Minor, both fixed: the sheet-file index bullet misdescribed suite: sheet notes do not move with row/column insert or delete #1335/Data Validation dialog: show Excel 2010 (x14) validations #1817 (every bullet was then re-checked against its file's sections, nine widened); the index check accepted an area file named anywhere in CLAUDE.md (now only its own Area notes bullet counts; 3 tests).
• review stopped: round 1 had no Major; all findings fixed

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[yeroo]

Merged automatically (auto-merge is on for this checkout): review stopped: round 1 had no Major; all findings fixed; merge rounds: none; whole suite green on 5d9560e (check-claude-md.py + 69 script unit tests; no Rust touched, CI 14/14 green); merge-check ok.

Follow-ups: none (no finding deferred).