Beagle SCM

JS-084 LOW: confirmed-minor correctness/perf cleanup batch

A batch of confirmed low-severity correctness/perf nits from the review, each a 1-2 line fix, grouped into ONE ticket (a TODO checkbox per item) to avoid ticket sprawl. Every cited file:line is verified below. The cheap ones land together; any item that grows past a couple of lines splits out into its own ticket. Repro where the bug is observable (the CR-in-line matcher, the oversized-line split, the empty-dir/dead-branch cases). Method: Issues.

Input

Context

• view/bro.js:67 io.mmap(path,"r").data() — the file mmap handle is never

  closed/unmapped (classify.js:125 already fled io.mmap for this leak).

• view/bro.js:88-91 buildDirHunk calls utf8.Encode(text) 3× per entry on

  the GROWING text → re-encodes the whole buffer each iteration, O(n^2).

• views/diff/diff.js:259-261 prefixingSink blind .split().join() rewrite

  of --- a//+++ b//diff: — matches those substrings anywhere in a chunk.

• core/loop.js:139-148 _hunkSink.feed 40-iteration retry cap + a substring

  ("" + e).includes("full") error match (fragile error classification).

• shared/store.js:358-367 readRecord retries on ANY caught error (comment

  says NOROOM) doubling cap to ~1GB before rethrow — a non-NOROOM error burns 24 grows.

• shared/store.js:277 locate: if (fileIdx < 0) return true; — an unknown

  (keeper-less) file_id is silently dropped, the scan continues.

• shared/pkt.js:30 if (total > 0xffff) throw — accepts total===0xffff,

  but 0xffff is the RESERVED pkt-line flush marker; should reject >=.

• shared/classify.js:122-139 wtEqBase reg-file path uses the lstat st.size

  from an EARLIER stat to size the read; a racing truncation → short read, stale-ok.

• core/job.js:57,85,107 c._read | 0 / startOff | 0 / c.after | 0 — the

  | 0 truncates the ULOG offset to 32-bit signed; a >2GB queue wraps.

• views/spot/match.js:77 splitLinesBytes line range {lo, hi:i} excludes

  \n but KEEPS a trailing \r — a CRLF source matches with the CR in-line.

• views/tree/tree.js:115-120 commitOrTree derefs tree/commit but

  returns null for a tag — an annotated tag is never dereferenced.

• views/blob/blob.js:122 if (sha === null) throw "BLOBFAIL" is DEAD —

  resolveHexAny returns undefined (store.js:344), never null, so an ambiguous prefix throws BLOBNONE, not BLOBFAIL.

• views/blob/blob.js:161-167 a single line longer than CAP (1 MiB) has no

  \n in [off,end), the back-scan hits off, if(nl>off) is false → the line is SPLIT mid-content rather than kept whole.

Goals

• Fix each nit with the minimal change; preserve byte-parity output.
• Repro the observable ones: full-line CR (match.js), oversized-line split

  (blob.js), the dead BLOBFAIL / empty-dir cases.

Constraints

• One file per item where possible (file-disjoint, parallel-safe). Keep each

  fix 1-2 lines; split any item that grows into its own ticket.

WIP

Design decisions

• Cheap fixes land in one changeset; CR-strip + oversized-line each get a

  repro. The error-classification nits (includes("full"), NOROOM retry) swap to a typed/NOROOM-specific check if the binding exposes one.

• job.js | 0 → Number()/BigInt-safe offset; verify the done-row format.

TODOs

• view/bro.js:67 close/unmap the file mmap after .data() (or fd-read

  like classify.js:125).

• view/bro.js:88-91 build the dir hunk with byte-length accumulation, not

  a per-entry full utf8.Encode.

• diff.js:259-261 anchor the prefix rewrite to line starts, not blind

  substring replace.

• loop.js:139-148 classify the grow error precisely (not `includes

  "full"`); revisit the 40-retry cap.

• store.js:358-367 readRecord retry-grow only on NOROOM, rethrow other

  errors immediately.

• store.js:277 locate — surface or log a keeper-less file_id rather than

  silently dropping it.

• pkt.js:30 reject total >= 0xffff (0xffff is the reserved marker).
• classify.js:122-139 re-lstat (or fstat the open fd) for the size used to

  read; guard the short read.

• job.js | 0 offsets: MOOT — core/job.js deleted with the work queue (JSQUE-020 928aaad5).
• Repro+fix match.js splitLinesBytes — strip a trailing \r from the line range (now ~:73-81).
• tree.js commitOrTree deref an annotated tag to its commit/tree (now :146-151, returns null for tag).
• blob.js dead BLOBFAIL: RE-EVAL — resolveHexOrFull now returns k.resolveHexAny(hex)||null

  (blob.js:69-72), so sha===null at :134 is REACHABLE, not dead; the original premise changed.

• Repro+fix blob.js oversized line split (now :174-179) — keep an oversized (>CAP, no-\n) line whole.

Blockers and bummers

• An item that needs a binding change (typed grow error, ambiguity signal)

  splits into its own ticket rather than bloating this batch.

• 2026-07-07 audit: 11 of 13 items STILL OPEN at shifted line refs — bro mmap view/bro.js:499;

  dir-hunk O(n²) bro.js:511-525; diff prefixingSink views/diff/diff.js:364-374; loop includes("full")+40-retry core/loop.js:80-83; store readRecord retry-any shared/store.js:359-368; store locate fileIdx<0 :278,:330; pkt >0xffff shared/pkt.js:30; classify stale st.size shared/classify.js:124-139 (switched mmap→fd read, race remains). Two changed: job.js item moot, blob.js dead-BLOBFAIL now reachable.

Outcome

• (pending)