Paijo 0eed344065 perf: Date.now hoist, hasActiveDeltaValue hoist, buffer.split guard in SSE stream (#7066) ...

* perf: hoist Date.now, hoist hasActiveDeltaValue, avoid per-chunk buffer.split in SSE stream

- Hoist  to transform entry, remove 2 inner
   declarations that shadowed the outer one (stream.ts)
- Hoist  from inline closure to module-level
  function to avoid allocation per chunk (stream.ts)
- Replace unconditional  per chunk with
  -gated split to avoid allocating array when
  no embedded newline (stream.ts streamHelpers.ts)
- Guard  to avoid allocating
  when already at/above limit

* fix: correct appendBoundedText slice offset when keep is zero

* chore(ci): rebaseline stream.ts 2796->2801 for perf/p1-fixes

Add _rebaseline_ entry documenting the +5 line growth from:
- da7b1e2b2: hoist Date.now, hoist hasActiveDeltaValue, avoid per-chunk split
- df89846cb: fix appendBoundedText slice offset when keep=0

These are irreducible optimizations at the stream dispatch chokepoint.

* chore: trigger CI re-run

* fix(#7066): bump stream.ts frozen baseline 2801->2802 (file grew +1 from parallel merges)

* fix(ci): shrink stream.ts under the frozen file-size cap instead of rebaselining

Two prior commits on this branch bumped config/quality/file-size-baseline.json
(2796->2801->2802) to accommodate this PR's own +6 line growth in
open-sse/utils/stream.ts, rather than fixing the cause. Per project policy the
baseline gate is a ratchet — it may only shrink, never grow to paper over a
regression.

Reverted both bogus rebaseline edits (file-size-baseline.json now matches
release/v3.8.49 exactly for this key) and instead extracted the two pure
helper functions this PR added/touched (appendBoundedText, hasActiveDeltaValue)
out of the god-file stream.ts into the existing sibling module
streamHelpers.ts, mirroring the extraction precedent already documented in
this baseline file. stream.ts now sits at 2778 lines (cap 2796); streamHelpers.ts
grew to 487 lines, well under its own 800-line new-file cap.

No behavior change — pure move. Verified via the existing
tests/unit/streamHelpers.test.ts (20/20) and the full createSSEStream test set
across 11 files (94/94), plus check:file-size, check:complexity,
check:cognitive-complexity, check:test-discovery, check:any-budget:t11, and
typecheck:core, all green.

Co-authored-by: diegosouzapw <diegosouza.pw@gmail.com>

* test(sse): cover appendBoundedText slice(-0) trap and hasActiveDeltaValue

Addresses the gemini-code-assist review finding on appendBoundedText. The
bug it describes (`keep === 0` -> `current.slice(-0)` returns the WHOLE
string, so the function returns current + next and blows past
STREAM_SUMMARY_TEXT_LIMIT) was real, and was already fixed on this branch
by df89846c — but with zero test coverage guarding it.

Both helpers were unexported internals of stream.ts and therefore untestable;
the extraction into streamHelpers.ts made them reachable, so this adds the
regression tests that lock the behavior in.

15 new tests. Verified as genuine guards, not decoration: temporarily
restoring the buggy `keep = LIMIT > next.length ? LIMIT - next.length : 0`
form makes exactly the two boundary tests fail ("next is exactly the limit"
and "next is larger than the limit"); restoring the fix makes all 35 pass.

Covers:
- appendBoundedText: empty next, normal concat, tail-keep at overflow,
  window slide at limit, next === limit (the slice(-0) trap), next > limit,
  and a 40-iteration loop asserting the bound never breaks.
- hasActiveDeltaValue: strings, null/undefined, empty/populated arrays and
  objects, nested recursion, and the number/boolean cases (0 and false are
  meaningful values, not absence).

Co-authored-by: diegosouzapw <diegosouza.pw@gmail.com>

---------

Co-authored-by: oyi77 <oyi77@users.noreply.github.com>
Co-authored-by: Diego Rodrigues de Sa e Souza <diegosouza.pw@gmail.com>

2026-07-19 20:52:35 -03:00

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