Fix embedded error-code detection in thrown-error rule

[Copilot]

require-error-code-in-thrown-error missed valid error-code constants when embedded after underscores, such as SAFE_OUTPUT_E099. This caused false positives in setup action scripts using SAFE_OUTPUT-style codes.

• Matcher
  • Recognize ERR_* and E### segments after identifier separators.
  • Preserve boundaries to reject partial matches such as SAFE_OUTPUT_E099X.

throw new Error(`${SAFE_OUTPUT_E099}: Failed to fetch review`);
throw new Error(`${MY_PREFIX_ERR_CONFIG}: Invalid configuration`);

• Regression coverage
  • Add valid template-literal cases for embedded numeric and named codes.
  • Add invalid cases for missing, extended, and embedded non-code tokens.

• Fixes eslint-factory: require-error-code-in-thrown-error false-positives on error-code identifiers embedded after an underscore #52643

---

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[github-actions]

✅ Test Quality Sentinel completed test quality analysis.

🧪 Test quality analysis by Test Quality Sentinel

[github-actions]

✅ Design Decision Gate 🏗️ completed the design decision gate check.

No ADR enforcement needed: PR #52972 does not have the 'implementation' label and has 0 new lines of code in business logic directories (2 files changed, none in src/, lib/, pkg/, internal/, app/, core/, domain/, services/, or api/).

🏗️ ADR gate enforced by Design Decision Gate 🏗️

[github-actions]

✅ Ponytail Reviewer completed successfully!

Lean already. Ship. Diff is a minimal regex fix (one-line change) plus targeted regression tests; no over-engineering, dead code, or speculative abstraction to cut.

Generated by Ponytail Reviewer for #52972

[github-actions]

🧠 Matt Pocock Skills Reviewer has completed the skills-based review. ✅

🧠 Reviewed using Matt Pocock's skills by Matt Pocock Skills Reviewer

[github-actions]

✅ PR Code Quality Reviewer completed the code quality review.

🔎 Code quality review by PR Code Quality Reviewer

[github-actions]

Comment Memory

reviewed_at: 2026-08-15T00:00:00Z
review_event: COMMENT
top_themes:
  - regex boundary fix looks correct
  - regression coverage added for embedded identifiers
  - no blocking issues found
files_reviewed:
  - eslint-factory/src/rules/require-error-code-in-thrown-error.ts
  - eslint-factory/src/rules/require-error-code-in-thrown-error.test.ts
comment_count: 0

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🔎 Code quality review by PR Code Quality Reviewer · gpt54 · 2.9 AIC · ⌖ 6.45 AIC · ⊞ 6.9K · ◷
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[github-actions]

Verdict

Non-blocking: the regex boundary change and accompanying regression cases look internally consistent, and I did not find a changed-line correctness or maintainability issue worth blocking this PR over.

Highlights

• The new negative-lookbehind still rejects partial suffix matches like SAFE_OUTPUT_E099X and ERR_CONFIGmore.
• The added tests cover both embedded numeric codes and embedded ERR_ segments, plus several nearby false-positive/false-negative cases.
• I did not find a missed changed-line edge case in the updated matcher logic.

🔎 Code quality review by PR Code Quality Reviewer · gpt54 · 2.9 AIC · ⌖ 6.45 AIC · ⊞ 6.9K
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[Copilot]

Pull request overview

Updates the ESLint rule to recognize error-code segments embedded after underscores without accepting partial matches.

Changes:

• Refines error-code boundary matching.
• Adds regression tests for valid embedded codes and invalid lookalikes.

Show a summary per file

File	Description
eslint-factory/src/rules/require-error-code-in-thrown-error.ts	Updates error-code detection boundaries.
eslint-factory/src/rules/require-error-code-in-thrown-error.test.ts	Adds embedded-code regression coverage.

Review details

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• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

[github-actions]

The regex fix is correct and well-tested.

Root cause: The old pattern \bERR_[A-Z_]+\b used \b word boundaries. Since _ is a word character, the boundary before ERR_ is not triggered when preceded by _ (e.g. MY_PREFIX_ERR_CONFIG). This made the rule miss valid error codes embedded after underscored prefixes.

Fix: The new pattern replaces \b with a negative lookbehind (?<![A-Za-z0-9]), anchoring only on alphanumeric characters. This correctly matches MY_PREFIX_ERR_CONFIG and SAFE_OUTPUT_E099 while still rejecting FOOERR_CONFIG, MY_PREFIX_ERROR_CONFIG, and other non-error-code names.

All new valid and invalid test cases are well-chosen and cover the key boundary conditions.

🧵 Reviewed using Impeccable skills by Impeccable Skills Reviewer · sonnet46 · 21.2 AIC · ⌖ 7.98 AIC · ⊞ 5.6K

[github-actions]

Skills-Based Review 🧠

Applied /diagnosing-bugs and /tdd — changes look correct, one minor comment suggestion.

📋 Key Themes & Highlights

Key Themes

• Correct root cause fix: Replacing \b with (?<![A-Za-z0-9]) so underscore serves as a valid separator is the right call — \b treats _ as a word character, which is why SAFE_OUTPUT_E099 failed to match.
• Good regression tests: Valid cases for SAFE_OUTPUT_E099 and MY_PREFIX_ERR_CONFIG plus invalid boundary cases (E099X, FOOERR_CONFIG, ERR_CONFIGmore) cover the interesting edges well.

One Minor Point

• The non-obvious choice of [A-Za-z0-9] over \b deserves a short inline comment to prevent a future simplification regressing the fix.

Positive Highlights

• ✅ Minimal, surgical change — 1 line of production code
• ✅ Regression tests added alongside the fix, matching /tdd red-green-refactor
• ✅ Both ERR_* and E### patterns updated symmetrically in the regex

🧠 Reviewed using Matt Pocock's skills by Matt Pocock Skills Reviewer · sonnet46 · 31.7 AIC · ⌖ 8.51 AIC · ⊞ 7.7K
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[github-actions]

[/diagnosing-bugs] The lookbehind uses [A-Za-z0-9] (not \b) to intentionally treat _ as a separator, enabling SAFE_OUTPUT_ERR_CONFIG to match while blocking FOOERR_CONFIG. Without a comment, a future maintainer may simplify this back to \b and re-introduce the bug.

💡 Suggested comment

// Use [A-Za-z0-9] — not \b — so underscore acts as a word separator.
// This lets SAFE_OUTPUT_ERR_CONFIG match while rejecting FOOERR_CONFIG.
const ERROR_CODE_PATTERN = /(?<![A-Za-z0-9])ERR_[A-Z_]+\b|(?<![A-Za-z0-9])E[0-9]{3}\b/;

@copilot please address this.

[github-actions]

🧪 Test Quality Sentinel Report

Summary

Test Quality Score: 92/100 ✅ Excellent

This PR adds 6 comprehensive test cases to validate the regex fix in the ESLint error-code detection rule. All tests directly validate the behavioral contract (pattern matching) with strong edge case coverage.

---

Test Analysis

Changed Files

File	Type	Changes
eslint-factory/src/rules/require-error-code-in-thrown-error.ts	Source	1 line (regex fix with negative lookbehind)
eslint-factory/src/rules/require-error-code-in-thrown-error.test.ts	Test	18 lines added (6 test cases)

Test Cases Added

Valid Pattern Cases (2 tests)

Test	Pattern	Why It Matters
SAFE_OUTPUT_E099	Numeric 3-digit code in template	Ensures numeric E[0-9]{3} pattern works
MY_PREFIX_ERR_CONFIG	Custom-prefixed error constant	Allows flexible naming conventions (e.g., PREFIX_ERR_*)

Classification: design_test, high_value — both validate the extended pattern range needed for real-world error codes.

Invalid Pattern Cases (4 tests) — Edge Cases for Negative Lookbehind

Test	Invalid Code	Pattern Violation	Why It Matters
MY_PREFIX_ERROR_CONFIG	Uses ERROR_ not ERR_	Wrong prefix pattern	Confirms only ERR_ and E[0-9]{3} are valid
SAFE_OUTPUT_E099X	Uses E099X (4 digits)	Numeric pattern boundary	Validates 3-digit constraint (E[0-9]{3})
ERR_CONFIGmore	ERR_CONFIG + trailing text	Negative lookbehind (char after)	Core fix validation: ensures alphanumeric cannot follow the pattern
FOOERR_CONFIG	Prefix + ERR_CONFIG	Negative lookbehind (char before)	Core fix validation: ensures alphanumeric cannot precede the pattern

Classification: design_test, high_value — the last two directly validate the negative lookbehind assertion fix ((?<![A-Za-z0-9])), which is the core improvement in this PR.

---

Quality Metrics

Metric	Result	Notes
Design Tests	100% (6/6)	All cases validate pattern-matching contracts
Edge Case Credit	83% (5/6)	Strong negative lookbehind boundary coverage
Duplication	0	Each case is a distinct pattern variant
Test Inflation	18:1	High but acceptable; ESLint rule tests use inline test data in RuleTester
Assertions	✅ Strong	Framework-based validation via ESLint RuleTester
Hard Violations	None	No mock libraries, no build-tag issues

---

Scoring Details

score = ((design_tests / total) * 40) +
        ((edge_tests / total) * 30) +
        (20 - duplicates * 5) +
        (inflation_ok ? 10 : 0)
      = (100% * 40) + (83% * 30) + 20 + 10 - 3
      = 92/100

Excellent threshold: ≥80 ✅

---

Recommendations

✅ All checks passed. The tests comprehensively validate the regex pattern fix with clear edge case scenarios. No changes needed.

Why this is high quality:

• Tests target design invariants (what patterns are/aren't valid)
• Tests validate the actual fix (negative lookbehind assertions)
• Edge cases cover pattern boundaries and constraints
• Follows standard ESLint testing patterns (RuleTester inline cases)
• Zero duplication or mock anti-patterns

🧪 Test quality analysis by Test Quality Sentinel · haiku45 · 23.1 AIC · ⌖ 3.59 AIC · ⊞ 7.9K · ◷
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[github-actions]

✅ Test Quality Sentinel: 92/100 Excellent. 100% design tests validating the regex pattern fix with comprehensive edge case coverage for negative lookbehind assertions. No hard violations. 0% implementation tests (threshold: 30%).

[gh-aw-bot]

@copilot Quick triage for maintainer-ready follow-up:

Please refresh the branch if needed, address the remaining maintainer-facing follow-up, and run the pr-finisher skill before handing this PR back to maintainers.

Outstanding review items (newest first):

• github-actions review: Fix embedded error-code detection in thrown-error rule #52972 (review) — add the short inline comment explaining why [A-Za-z0-9] is used instead of ``, so the regex boundary fix does not get simplified away later.

Failed checks from the compact candidate set:

• None listed.

Branch update was requested automatically for this run when GitHub allows it.
Run context: https://github.com/github/gh-aw/actions/runs/31911601861

Generated by 👨‍🍳 PR Sous Chef · gpt54 · 18.4 AIC · ⌖ 6.84 AIC · ⊞ 8.7K · ◷
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[github-actions]

🎉 This pull request is included in a new release.

Release: v0.87.0