fix(kiro): split escaping from framing using the measured wire model - #3488
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The context estimate still read 0.884 of what Kiro charges, and the shortfall
grew with conversation length: 0.918 at four messages down to 0.878 at seven
hundred. A residual that tracks entry count is a per-entry cost, not a
per-character one.
Regressing serialized bodies against what the payload walker counts, over
eleven sizes from 3 to 701 entries:
bodyBytes = 1.0422 * walkedChars + 66.7 * entries + 68
Per-entry framing is 66.7 bytes, which at 2.433 bytes per charged token is 27.4
tokens — more than double the 12 we charged. That hand-fit predated this
regression, and being less than half the real cost is exactly why the estimate
decayed with length: an under-charge of ~15 tokens per entry is invisible across
four messages and dominant across seven hundred.
The escape multiplier moves 1.12 -> 1.20 for a reason worth stating, because
the first reading of that regression suggested the opposite. 1.0422 is bytes per
walked CHARACTER, but the multiplier applies to TOKENS. The shared estimator
counts Latin text at 2.8 chars/token while the wire charges an effective
2.433/1.0422 = 2.334, and 2.8/2.334 = 1.199.
The evidence that this split is the right one is its stability: holding framing
at 27, the multiplier the charge implies stays within 1.189-1.209 across a 230x
range of conversation sizes. A mis-specified split drifts with size, and the old
pair did.
Aggregate estimate/charged 0.884 -> 1.002, and the spread across 4 to 700
messages collapses from 0.050 to 0.006. Cross-checked against 4,090 recorded
requests (framing is 5% of a real message's cost, so it is not absorbing
content) and against the pathological shape of many tiny turns, where the old
constants read 0.497 and the new ones read 0.970.
The new test asserts the relationship rather than the constants: adding turns
that carry almost no text must still raise the estimate, which a
text-proportional multiplier cannot do. It fails if framing is folded away.
Three assertions that pinned exact checkpoint totals are now relations, since
they were snapshots of these constants rather than statements about behavior.
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📝 WalkthroughWalkthroughThe Kiro adapter now estimates serialized payload tokens with separate Latin and CJK handling, higher entry framing, and updated wire calibration. Stream tests validate relational context estimates, entry growth, tool payloads, and language-specific scaling. Calibration documentation describes least-recently-used eviction. ChangesKiro token estimation
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: 🟡 Moderate · up to Kiro context estimates now use higher framing and script-aware wire sizing, but Arabic, Cyrillic, Thai, and other non-CJK scripts can be overestimated and compacted early. The language classification and regression bound should be corrected before merge. Suggested reviewers: 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
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Inline comments:
In `@tests/kiro-stream.test.ts`:
- Around line 1832-1835: Strengthen the calibration regression coverage in
tests/kiro-stream.test.ts: at lines 1832-1835 raise the per-entry lower bound
above the former 12-token framing value and add an escape-heavy payload case
rejecting the former 1.12 multiplier; retain bounded checkpoint assertions at
lines 1504-1518, 1615-1617, and 1756-1757 that reject the former calibration
values while preserving the existing shape checks.
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| // 80 near-empty turns carry only ~160 chars of text between them, so anything beyond a | ||
| // couple of tokens per entry can only come from a per-entry structural charge. | ||
| expect(perEntry).toBeGreaterThan(10); | ||
| expect(perEntry).toBeLessThan(60); |
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🎯 Functional Correctness | 🟡 Minor | ⚡ Quick win
Add a calibration-sensitive regression assertion.
The previous model passes every changed assertion. The former checkpoints of 298, 420, and 2663 exceed the new lower bounds. The former 12-token framing charge also passes 10 < perEntry < 60. A revert of both revised constants can therefore pass this test suite.
Keep the shape checks. Add a bounded assertion that rejects the former framing value, such as perEntry > 20, and add an escape-heavy payload case that rejects the former 1.12 multiplier.
tests/kiro-stream.test.ts#L1832-L1835: raise the lower per-entry bound above the former 12-token framing behavior.tests/kiro-stream.test.ts#L1504-L1518: retain a bounded checkpoint assertion that rejects the former calibration.tests/kiro-stream.test.ts#L1615-L1617: retain a bounded checkpoint assertion that rejects the former calibration.tests/kiro-stream.test.ts#L1756-L1757: retain a bounded checkpoint assertion that rejects the former calibration.
As per path instructions, “A behavior change in src/ should come with a focused regression test near the existing tests for that subsystem.”
📍 Affects 1 file
tests/kiro-stream.test.ts#L1832-L1835(this comment)tests/kiro-stream.test.ts#L1504-L1518tests/kiro-stream.test.ts#L1615-L1617tests/kiro-stream.test.ts#L1756-L1757
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In `@tests/kiro-stream.test.ts` around lines 1832 - 1835, Strengthen the
calibration regression coverage in tests/kiro-stream.test.ts: at lines 1832-1835
raise the per-entry lower bound above the former 12-token framing value and add
an escape-heavy payload case rejecting the former 1.12 multiplier; retain
bounded checkpoint assertions at lines 1504-1518, 1615-1617, and 1756-1757 that
reject the former calibration values while preserving the existing shape checks.
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Source: Path instructions
리뷰 · 우선순위 66 / 80설명 이 PR은 방금 지금 그래서 이 PR은 직렬화 body를 walker가 센 글자 수에 대해 회귀한 식 을 근거로 framing을 12→27로 올리고, escape 배율을 1.12→1.20으로 바꾼다. 배율 쪽 설명도 중요하다. 테스트 쪽 변화도 같은 철학이다. 현재 구조라서, 이 PR은 그 식의 계수만 실측으로 갈아끼우는 작업이다. types.ts/config.ts 분할 캠페인과도 무관하고, 닫을 중복도 아니다. 같은 파일 라인 219 - 메인테이너의 판단이 필요한 지점
너의 추천 이 댓글은 grok-bot이 작성했습니다 |
The entry-count test used a 10..60 band, and both the old 12-token framing charge (13.2 per entry) and the new measured 27-token one (28.3) fit inside it. Reverting both constants passed the whole suite, so the test asserted that SOME per-entry cost exists without asserting the measured one — which is not what the change is about. Tightened to 20..40. That still expresses the shape rather than restating a constant, and it now separates the two models: the ablation with the old pair restored fails this test rather than passing. Also corrects the MAX_TRACKED_CONVERSATIONS comment, which still described insertion-order eviction. touch() re-inserts on every estimate and observation, so eviction is least-recently-used; insertion order would have evicted the long active conversation that is most worth keeping. Found in review of f61eb0e.
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Exact head 3431665 now correctly tightens the per-entry regression so the former 12-token framing value fails. One half of the calibration change is still unproved: reverting only KIRO_JSON_ESCAPE_EXPANSION from 1.20 to 1.12 still satisfies every changed assertion. Please add a focused fixed-payload/escape-heavy regression with a bounded estimate (or an equivalent relation that isolates the text multiplier after accounting for entry framing) so 1.12 fails while the measured 1.20 model passes. Keep the new 20..40 entry-cost shape test. After that and the #3487 merge-order rebase, rerun exact-head CI.
The 1.2 factor is derived from 2.433 bytes per charged token, and that rate is a property of this traffic mix — Latin and code. A Hangul character is three UTF-8 bytes but roughly one token, so a Latin-derived byte rate says nothing about it. Scaling the whole estimate by 1.2 therefore billed Hangul at 1.25 chars/token. Against recorded ground truth, which pairs exact text with authoritative input token counts and is script-independent, that reads 1.079 of what CJK-heavy input is actually charged. Applying the factor to the Latin term alone brings it to 0.988 and leaves Latin unchanged at 1.199. Over-charging Korean threads would have compacted them early, which is the same class of bug in the other direction. Also corrects the constant's name and its comment. It was called KIRO_JSON_ESCAPE_EXPANSION and described as JSON escaping, which it is not: measured directly, JSON.stringify expands prose by 1.012 (Latin) to 1.019 (Korean), nowhere near 1.2. Escaping is real but small and already inside the byte measurement the factor comes from. The name now says what it is. Adds a regression pinning the Korean estimate against the ratio the shared estimator already encodes; it fails if the expansion is moved back onto the whole blob. Found in review of f61eb0e.
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The CJK/Latin split on exact head bd0a13e is a sound correction, and the new Korean regression proves that the Latin multiplier is not applied to CJK. It still does not prove the measured Latin multiplier itself. I checked this with an isolated mutation test: changing only KIRO_LATIN_WIRE_EXPANSION from 1.20 back to 1.12 leaves tests/kiro-stream.test.ts fully green (113/113, Bun 1.4.0, protected runtime unchanged). The tool-heavy 0.8..1.0 wire bound and Korean assertions both admit 1.12. Please add a fixed Latin/code-heavy payload assertion whose bounded estimate rejects 1.12 while accepting the measured 1.20 model. Keep the CJK and entry-shape coverage; those validate different axes. Then rerun exact-head CI, and rebase after #3487 lands as already planned.
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Inline comments:
In `@src/adapters/kiro.ts`:
- Around line 211-212: Update the token estimation logic around
estimateKiroTokens so KIRO_LATIN_WIRE_EXPANSION applies only to actual Latin
characters, not merely text without CJK characters. Count Latin and non-Latin
contributions separately instead of converting every non-CJK character to “x”,
preserve each script’s token classification, and add a regression case covering
a non-Latin, non-CJK script.
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| if (cjk === 0) return Math.ceil(estimateKiroTokens(text, modelId) * KIRO_LATIN_WIRE_EXPANSION); | ||
| const latinTokens = estimateKiroTokens("x".repeat(text.length - cjk), modelId); |
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🎯 Functional Correctness | 🟠 Major | ⚡ Quick win
Restrict the expansion to actual Latin text.
Line 211 applies KIRO_LATIN_WIRE_EXPANSION to any text that has no Hangul, Han, or kana. Arabic, Cyrillic, Thai, and other non-Latin scripts therefore receive the Latin factor. Line 212 also converts all non-CJK characters to "x", which removes their script classification.
This does not meet the stated Latin-only calibration. It can overestimate affected conversations and compact them early. Count Latin characters separately, apply the factor only to their token contribution, and add a regression case for a non-Latin, non-CJK script.
🤖 Prompt for AI Agents
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In `@src/adapters/kiro.ts` around lines 211 - 212, Update the token estimation
logic around estimateKiroTokens so KIRO_LATIN_WIRE_EXPANSION applies only to
actual Latin characters, not merely text without CJK characters. Count Latin and
non-Latin contributions separately instead of converting every non-CJK character
to “x”, preserve each script’s token classification, and add a regression case
covering a non-Latin, non-CJK script.
After applying the fix, consider running `coderabbit review --agent` for local
review. Visit https://docs.coderabbit.ai/cli.
2 participants
Summary
Follow-up to #3476, which left the Kiro context estimate at 0.884 of what Kiro charges with a shortfall that grew with conversation length — 0.918 at four messages down to 0.878 at seven hundred. A residual that tracks entry count is a per-entry cost, not a per-character one.
Regressing serialized bodies against what the payload walker counts, over eleven sizes from 3 to 701 entries:
Per-entry framing is 66.7 bytes, which at the measured 2.433 bytes per charged token is 27.4 tokens — more than double the 12 we charged. That 12 was a conservative hand-fit made before this regression existed, and being less than half the real cost is exactly why accuracy decayed with length: an under-charge of ~15 tokens per entry is invisible across four messages and dominant across seven hundred.
The escape multiplier moves 1.12 → 1.20, and the reason is worth stating because my first reading of the regression suggested the opposite.
1.0422is bytes per walked character, but the multiplier applies to tokens. The shared estimator counts Latin text at 2.8 chars/token while the wire charges an effective2.433 / 1.0422 = 2.334, and2.8 / 2.334 = 1.199.The evidence that this split is correct is its stability: holding framing at 27, the multiplier implied by the charge stays within 1.189–1.209 across a 230x range of conversation sizes. A mis-specified split drifts with size, and the old pair did.
Cross-checked two ways. Against 4,090 recorded requests, where real traffic averages 1,310 bytes per message: 66.7 bytes is 5% of that, so the framing term charges framing and is not quietly absorbing message content. And against the pathological shape of many tiny turns, where a per-entry floor is most likely to over-count — the old constants read 0.497 there, the new ones read 0.970, and nothing over-counts.
Verification
bun test tests/kiro-stream.test.ts tests/kiro-calibration.test.ts tests/token-estimate.test.ts tests/input-admission.test.ts tests/kiro-adapter.test.ts tests/core-lab-boundary.test.ts— 263 pass, 0 failbun x tsc --noEmit— cleanbun run privacy:scan— passedbuildKiroPayload, not a mirrored copy of itThe new test asserts the relationship rather than the constants: adding turns that carry almost no text must still raise the estimate, which a text-proportional multiplier cannot do. It was driven red by zeroing the framing term to prove it is not vacuous. Three assertions that pinned exact checkpoint totals became relations, since they were snapshots of these constants rather than statements about behaviour.
The repository-wide suite was not run locally; CI covers it. No
gui/file is touched.Checklist
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