[codeasier]

Fork-local fix for the reproduced hook truncation regression (risk-list item 1). Not an upstream port.

The regression

The hook's 32k structure-preserving wire bound sliced strings by raw character count. JSON escaping (quotes, backslashes, control characters) can double or triple the serialized form, so a "truncated" string could still exceed its budget. The object accounting's cost check then rejected the field, and the loop's break discarded every remaining field. Reproduced with the pre-fix code:

input : { stdout: '"'.repeat(60000), file_path: '/very/important/path.ts', exit_code: 0 }
output: {}          # every field lost — file_path included

Quote-heavy stdout is exactly what serialized-JSON tool outputs look like, so this fired on real captures.

The fix

Truncation moves to src/hooks/truncate.ts (importable, sdk-guard.ts pattern) and now mirrors the server's boundValue in src/functions/observe.ts:

1. Strings cut by binary search on serialized length (the server's boundString algorithm) — the delivered form always fits its budget.
2. Object fields taken smallest-first (decorate-sort-undecorate by serialized size) — a huge stdout cannot crowd out file_path/exit_code. Field order changes in transit only; the server re-bounds and re-orders anyway.
3. Unfittable entries skipped, not fatal (break → continue in the entry loops) — long primitives or sub-marker budgets no longer discard later fittable entries.

Built copies in dist/hooks/ and plugin/scripts/ regenerate via npm run build.

Verification

• New test/post-tool-use-truncation.test.ts: 17 tests (serialized-length bound, smallest-field survival, skip-not-stop, passthrough, nested budgets)
• npm test: 1861 passed, 1 skipped (baseline 1844 + 17)
• npx tsc --noEmit: identical error set to the post-fix(cli): make fresh installs portable and persistent #8 baseline (31 normalized lines, zero new)
• End-to-end against the built plugin/scripts/post-tool-use.mjs with a mock REST sink: 60k-quote stdout payload delivers {exit_code, file_path, stdout: truncated} at 31999/32000 serialized chars — the previous build delivered {}
• npm run build: clean; plugin script verified to contain the binary search + sort + continues