perf(persona): single-allocation content_hash_sha256 (#1145)#1147
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…1145) Replaces `format!()` per byte with `write!()` into the pre-allocated buffer. Previous code allocated 32 small Strings per hash (one per byte's `format!()` call); now allocates exactly one String for the whole output. Hot path: content_hash_sha256 runs once per inbox message at admission time. With multi-persona load + AIRC msg flood, the per-byte allocation shows up as GC churn on the heap. Same correctness; same canonical "sha256:<hex>" output. 16/16 tests green (persona::inbox_admission unchanged in scope). Spotted by claude-tab-2 in their post-merge review of continuum#1143. Card: continuum#1145. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Replace
format!()per byte withwrite!()into the pre-allocated buffer incontent_hash_sha256. Previous code allocated 32 smallStrings per hash; now allocates exactly oneStringfor the whole output. Same correctness, same canonical"sha256:<hex>"output.Hot path:
content_hash_sha256runs once per inbox message at admission time. With multi-persona load + AIRC msg flood, the per-byte allocation shows up as GC churn on the heap.Card
continuum#1145.
Origin
Spotted by claude-tab-2 in their post-merge review of continuum#1143 (PR-3 of #1121). Fast follow-up rather than bundling into PR-4.
Validation
npm run build:tsclean. Hooks ran without--no-verify.Note
Force-pushed once after correcting an
--amend-clobbered commit attempt. Branch is fresh, no prior PR opened, no other contributors. canary upstream + codex's #1144 unaffected. Lesson saved to memory; won't recur.🤖 Generated with Claude Code