test: property-check display-width clustering and parseKey totality

[ndycode]

Summary

• Adds a fast-check property suite for the layer beneath test: property-check table formatter alignment under unicode content #595: lib/ui/display-width.ts (the ui-02 column-measurement implementation with grapheme clustering) and lib/ui/ansi.ts's parseKey (raw stdin bytes → key action, which must be total).

What Changed

New test/property/display-width.property.test.ts (6 properties):

display-width — generated over an adversarial alphabet that includes every cluster mechanic the implementation special-cases (ZWJ, variation selector-16, combining keycap, combining accents, skin-tone modifiers, regional indicators, CJK, emoji):

1. Totality and bounds — displayWidth returns a non-negative integer bounded by two columns per code point, for any combination including pathological joiner/modifier soup.
2. Plain-alphabet oracle — with no joiners/modifiers present, width equals the per-character sum and concatenation is exactly additive — the standing assumption the table formatter's geometry rests on (deliberately not asserted for the adversarial alphabet, where VS-16 promotion makes concatenation legitimately non-additive).
3. Truncation contract — truncateToWidth returns a prefix whose reported width is displayWidth of the kept text (self-consistency between the two exports), never exceeds the budget, stops early only when the remaining gap is 0–1 columns (clusters max out at 2, so a 2-column gap proves the next cluster would have fit), and is idempotent.
4. Budget monotonicity — widening the budget only ever extends the kept prefix.

parseKey:

5. Totality — arbitrary byte buffers always produce a member of the KeyAction union; no input throws.
6. Table fidelity — all 16 recognized ANSI sequences map to their documented actions, and every other generated string maps to null.

No SUT bugs found.

Validation

• npm test -- test/property/display-width.property.test.ts test/display-width.test.ts test/ansi.test.ts — 25/25 (new 6 + existing suites untouched)
• npm run typecheck (also via pre-commit hook)
• npx eslint test/property/display-width.property.test.ts --max-warnings=0

Docs and Governance Checklist

• Test-only; no behavior or docs surface changed

Risk and Rollback

• Risk level: minimal — additive test file; conventions match the existing test/property/ suites.
• Rollback plan: revert the single commit.

https://claude.ai/code/session_01XNtnkLbBiXZxfQQYLMpucB

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Generated by Claude Code

note: greptile review for oc-chatgpt-multi-auth. cite files like lib/foo.ts:123. confirm regression tests + windows concurrency/token redaction coverage.

Greptile Summary

adds a property-based test file covering displayWidth/truncateToWidth (6 properties over an adversarial grapheme-cluster alphabet) and parseKey totality + table fidelity. no sut code is changed.

• display-width suite: totality/bounds, plain-alphabet oracle, truncation self-consistency + maximality + idempotence, and budget monotonicity — the step assertion in the monotonicity property explicitly self-enforces the "no cluster wider than 2" assumption that the maximality bound relies on.
• parseKey suite: arbitrary byte-buffer totality via fc.uint8Array, and an exact-match table check for all 16 documented ansi sequences followed by a property asserting every other generated string maps to null.

Confidence Score: 5/5

additive test file only; no sut code touched and no filesystem or token handling introduced.

every changed line is a new test. the property invariants are logically correct — oracle values checked against the sut, all 16 ansi sequences in the fidelity table match the implementation exactly, and the monotonicity step assertion self-enforces the cluster-width assumption that the maximality bound relies on. no concurrency, windows-path, or token-safety concerns arise in a stateless property suite.

no files require special attention.

Important Files Changed

Filename	Overview
test/property/display-width.property.test.ts	new property suite — 6 tests, logically sound; all oracle values verified against the sut, the ansi table matches all 16 sut branches exactly, and the step assertion makes the cluster-width assumption explicit.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[display-width.property.test.ts] --> B[display-width invariants]
    A --> C[parseKey invariants]

    B --> D["totality & bounds\narbAdversarialText → non-neg int ≤ codePoints×2"]
    B --> E["plain-alphabet oracle\narbPlainText → sum matches per-char + additive split"]
    B --> F["truncation contract\nself-consistency · in-budget · prefix · maximality · idempotence"]
    B --> G["budget monotonicity\nnarrower prefix ⊆ wider prefix · step width ≤ narrow+2"]

    C --> H["totality\nfc.uint8Array → always a known KeyAction"]
    C --> I["table fidelity\n16 ANSI sequences exact-match · fc.string !known → null"]

    F -->|depends on| J["cluster width ≤ 2\n(assumed)"]
    G -->|self-enforces| J

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: 1a5f99eb-c584-44f6-9664-9d51f0366670

📥 Commits

Reviewing files that changed from the base of the PR and between dae10cb and 70707c9.

📒 Files selected for processing (1)

• test/property/display-width.property.test.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/audit-79-display-width-property

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/audit-79-display-width-property

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