refactor: eliminate near-duplicate string utilities, promote general-purpose helpers to pkg/stringutil

[Copilot]

Addresses three findings from semantic function clustering analysis: one confirmed near-duplicate, two general-purpose utilities misplaced in the workflow package.

Changes

Remove extractStringSlice duplicate (compiler_experiments.go)

• Replaced both extractStringSlice(raw) calls with parseStringSliceAny(raw, nil) — the canonical version already in parse_helpers.go
• Deleted extractStringSlice; the canonical version also handles nil input and pre-allocates the result slice

Promote formatList → stringutil.FormatList

• Moved from private workflow/strings.go to exported pkg/stringutil/stringutil.go
• Fixed a latent recursion bug: 3-item input previously produced "a and b, and c" instead of "a, b, and c"; replaced recursion with strings.Join:

  // before (recursive, buggy for 3+ items)
  return fmt.Sprintf("%s, and %s", formatList(items[:len(items)-1]), items[len(items)-1])
  
  // after (correct Oxford comma)
  return strings.Join(items[:len(items)-1], ", ") + ", and " + items[len(items)-1]

• Updated tools_validation_github_toolsets.go to use stringutil.FormatList

Promote normalizeLeadingWhitespace → stringutil.NormalizeLeadingWhitespace

• Moved from private unified_prompt_step.go to exported pkg/stringutil/stringutil.go
• Fixed indentation measurement to use strings.TrimLeft(line, " \t") instead of strings.TrimLeft(line, " ") so that tab-indented and mixed tab/space indented content is correctly dedented
• Updated both call sites in unified_prompt_step.go and the existing test

Tests

• Added TestFormatList and TestNormalizeLeadingWhitespace to pkg/stringutil/stringutil_test.go, including tab-indentation and mixed-indentation test cases

No change needed

• close_entity_helpers.go already contains the architectural comment explaining the registry-vs-per-file choice

[github-actions]

Hey @copilot-swe-agent 👋 — great work on the string-utility refactoring! Eliminating the extractStringSlice duplicate, fixing the latent Oxford-comma recursion bug in formatList, and promoting both helpers to pkg/stringutil are all solid, well-described changes. Tests are included too — nice.

One thing worth tidying up before merge:

• Unrelated files in the diff — the PR includes changes to .github/workflows/metrics-collector.lock.yml, docs/src/content/docs/agent-factory-status.mdx, and docs/src/content/docs/reference/frontmatter-full.md, none of which are explained in the PR body. If these were auto-generated side-effects of running the pipeline, a brief note in the description would clarify intent; if they were picked up unintentionally, they should be reverted or split into a separate PR.

If you'd like a hand cleaning this up, here's a ready-to-run prompt:

In PR #30249 (refactor: eliminate near-duplicate string utilities), three files appear to be unrelated to the string-utility changes:
- .github/workflows/metrics-collector.lock.yml
- docs/src/content/docs/agent-factory-status.mdx
- docs/src/content/docs/reference/frontmatter-full.md

Investigate whether these files were changed intentionally as part of this refactor:
1. If they are auto-generated artifacts that were unintentionally picked up, revert them to their state on the base branch.
2. If they are intentional updates unrelated to the refactor, move them to a separate PR.
3. If they are legitimately coupled to the refactor, add a brief explanation to the PR body describing why.

Generated by Contribution Check · ● 1.4M · ◷

[Copilot]

Pull request overview

Refactors duplicate/general-purpose string helpers into pkg/stringutil, updates workflow call sites, and removes one duplicate experiment slice parser. The diff also includes some unrelated docs/workflow metadata edits outside the stated refactor scope.

Changes:

• Moved formatList and normalizeLeadingWhitespace into pkg/stringutil and updated workflow usages/tests.
• Replaced duplicate extractStringSlice calls in experiment parsing with the canonical parseStringSliceAny.
• Also changed OTLP reference docs, agent-factory status docs, and one generated workflow lockfile.

Show a summary per file

File	Description
pkg/workflow/unified_prompt_step.go	Swaps local whitespace normalization calls to stringutil.NormalizeLeadingWhitespace.
pkg/workflow/unified_prompt_step_test.go	Updates the prompt-step test to call the moved helper.
pkg/workflow/tools_validation_github_toolsets.go	Replaces local list formatting with stringutil.FormatList in validation errors.
pkg/workflow/strings.go	Removes the old private formatList implementation.
pkg/workflow/compiler_experiments.go	Reuses parseStringSliceAny instead of the deleted duplicate slice parser.
pkg/stringutil/stringutil.go	Adds exported FormatList and NormalizeLeadingWhitespace.
pkg/stringutil/stringutil_test.go	Adds direct tests for the promoted string utilities.
docs/src/content/docs/reference/frontmatter-full.md	Expands OTLP endpoint reference docs; appears unrelated to the refactor.
docs/src/content/docs/agent-factory-status.mdx	Adds three agent-factory table rows; appears unrelated to the refactor.
.github/workflows/metrics-collector.lock.yml	Adds one workflow env version line in a generated lockfile.

Copilot's findings

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• Files reviewed: 10/10 changed files
• Comments generated: 3

[pelikhan]

@copilot review all comments

[Copilot]

@copilot review all comments

Addressed in 9a7a99e:

1. Tab indentation in NormalizeLeadingWhitespace: Fixed the indentation counting to use strings.TrimLeft(line, " \t") instead of strings.TrimLeft(line, " "), so tabs and mixed tab/space indentation are now handled correctly. Added test cases for both.

2. Unrelated docs/lockfile changes: Reverted docs/src/content/docs/agent-factory-status.mdx, docs/src/content/docs/reference/frontmatter-full.md, and .github/workflows/metrics-collector.lock.yml to their original state — these were accidentally included from other in-flight changes in the branch.