fix(engine): pre-expand brace patterns with path separators in ctx.glob()

[rhuanbarreto]

Summary

• Work around oven-sh/bun#32596: Bun.Glob.scan() silently returns empty results for brace patterns whose alternatives contain path separators (e.g. svc/{src/env.ts,env.ts}), while match() handles them correctly
• Add expandBracePattern() that detects {alt1,alt2} groups containing / and expands them into separate patterns before scanning — simple braces without / pass through unchanged
• Applied in ctx.glob(), ctx.grepFiles(), and resolveScopedFiles() so rule authors and ADR files: globs work correctly with brace expansion

Closes #421

Test plan

• Unit tests for expandBracePattern() — no braces, simple braces (no /), braces with /, multiple alternatives, suffix handling, no-prefix patterns
• Integration tests for ctx.glob() and ctx.grepFiles() with brace patterns containing path separators
• Integration test for resolveScopedFiles() with brace patterns containing path separators
• Regression test that simple braces (no /) still work natively via Bun.Glob
• bun run validate passes (lint, typecheck, format, 1303 tests, 39/39 ADR rules, knip, build)

https://claude.ai/code/session_01C3VSm9YHmfhZ9kLw2fkLE4

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[github-actions]

Code Coverage

Metric	Value
Lines	90.4% (6888 / 7616)
Threshold	90% minimum — met
Platforms	Linux + Windows

Full HTML report available in workflow artifacts.

Per-directory breakdown

Directory	Coverage	Lines
src/commands/	88.1%	1874 / 2128
src/engine/	93.3%	1418 / 1520
src/formats/	100.0%	142 / 142
src/helpers/	90.3%	3454 / 3826

[coderabbitai]

📝 Walkthrough

Walkthrough

The PR fixes a silent Bun.Glob.scan() failure where brace patterns containing path separators (e.g., svc/{src/env.ts,env.ts}) return zero matches. A new exported expandBracePattern() function is added to runner.ts; it detects brace groups whose alternatives include / and pre-expands them into separate flat patterns. This expansion is applied in the glob() and grepFiles() rule-context methods in runner.ts, and also in resolveScopedFiles() in git-files.ts. Both call sites now deduplicate results via a Set. Unit tests cover all expandBracePattern edge cases, and regression tests validate the fix for ctx.glob, ctx.grepFiles, and resolveScopedFiles. Agent memory notes document the root cause and a related lint false-positive.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: fixing a bug where ctx.glob() fails with brace patterns containing path separators by pre-expanding them.
Description check	✅ Passed	The description is directly related to the changeset, explaining the Bun.Glob bug, the expandBracePattern solution, and its three application points with comprehensive testing.
Linked Issues check	✅ Passed	The PR fully addresses issue #421 by implementing brace expansion support in ctx.glob(), ctx.grepFiles(), and resolveScopedFiles() to eliminate the silent failure when patterns contain path separators.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to implementing and testing the brace pattern expansion fix; documentation additions and test coverage are all aligned with the stated objectives.
Docstring Coverage	✅ Passed	Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/glob-brace-expansion-421

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/engine/runner.ts`:
- Around line 87-98: The expandBracePattern function returns the pattern
unchanged when the first brace group lacks a forward slash, but this skips
checking for subsequent brace groups that may contain slashes and need
expansion. Instead of the early return when `!alternatives.includes("/")`,
recursively process the suffix by calling expandBracePattern on the suffix
parameter and combine each result with the prefix to properly handle multi-brace
patterns like `a/{b,c}/{d/e,f}` where later brace groups contain slashes even
though earlier ones do not.

In `@tests/engine/expand-brace-pattern.test.ts`:
- Around line 14-46: The test suite for expandBracePattern is missing coverage
for patterns with multiple brace groups at the same nesting level. Add a new
test case within the describe("expandBracePattern", ...) block that tests a
pattern like "a/{b,c}/{d/e,f}" to document the current behavior and serve as a
regression check. This test should verify how the function handles multiple
independent brace groups in a single pattern and will establish baseline
behavior for this scenario.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: ebfdba52-ef57-45a7-99ee-31a6b198f799

📥 Commits

Reviewing files that changed from the base of the PR and between aa436e6 and 31bff05.

📒 Files selected for processing (5)

• .claude/agent-memory/archgate-developer/MEMORY.md
• src/engine/git-files.ts
• src/engine/runner.ts
• tests/engine/expand-brace-pattern.test.ts
• tests/engine/git-files.test.ts

[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

src/engine/runner.ts (1)

159-163: ⚠️ Potential issue | 🔴 Critical

Add re-validation of expanded patterns to prevent absolute-path bypass.

safeGlob() runs only on the raw input pattern, but expandBracePattern() can produce absolute patterns that were never validated. For example, a pattern like {/absolute/path/*,relative/*} bypasses the initial check because isAbsolute() on the raw string returns false (it starts with {), yet the expansion yields an absolute pattern that Bun.Glob may not sandbox to the project root.

Suggested fix

@@
       const patterns = expandBracePattern(pattern);
       const seen = new Set<string>();

       for (const p of patterns) {
+        safeGlob(p);
         const g = new Bun.Glob(p);
@@
       const globs = expandBracePattern(fileGlob);

@@
       const seen = new Set<string>();
       for (const p of globs) {
+        safeGlob(p);
         const g = new Bun.Glob(p);

Apply at both locations: lines 161 and 207.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/engine/runner.ts` around lines 159 - 163, The expandBracePattern()
function can produce absolute paths that bypass the initial safeGlob()
validation since the raw input pattern may not be absolute (e.g., starting with
a brace character). Add validation of each expanded pattern in the patterns
array after expandBracePattern() is called but before they are used with
Bun.Glob. Check each pattern returned by expandBracePattern() with isAbsolute()
to ensure no absolute paths are processed, and apply this same validation at
both occurrences where expanded patterns are used (around line 161 in the loop
iteration and at line 207).

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Outside diff comments:
In `@src/engine/runner.ts`:
- Around line 159-163: The expandBracePattern() function can produce absolute
paths that bypass the initial safeGlob() validation since the raw input pattern
may not be absolute (e.g., starting with a brace character). Add validation of
each expanded pattern in the patterns array after expandBracePattern() is called
but before they are used with Bun.Glob. Check each pattern returned by
expandBracePattern() with isAbsolute() to ensure no absolute paths are
processed, and apply this same validation at both occurrences where expanded
patterns are used (around line 161 in the loop iteration and at line 207).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: c8502793-518b-4711-86c7-7fe8949f4916

📥 Commits

Reviewing files that changed from the base of the PR and between 31bff05 and 66ce3cd.

📒 Files selected for processing (2)

• src/engine/runner.ts
• tests/engine/expand-brace-pattern.test.ts