fix: drop non-string scalar aliases in metadata conversion

[RAIT-09]

Description

Follow-up to #377, covering the remaining CodeRabbit comment: the scalar branch of convertToMetadata() was still unfiltered, so a truthy non-string scalar (e.g. aliases: 42) leaked into NoteMetadata as [42].

Instead of patching that one branch, this centralizes frontmatter alias normalization into a single module-level helper (normalizeFrontmatterAliases) used by both searchNotes() and convertToMetadata() — the duplicated, slightly different normalization is what let the two sites drift apart in the first place. The helper takes unknown and proves stringness with a type predicate, which also removes the misleading as string[] | string | undefined casts (the root cause behind the crash in #354).

Also included:

• "No aliases" is now consistently represented as undefined in NoteMetadata (previously undefined or [] depending on the input shape; the field has no consumers).
• Prettier normalization of the lines introduced in fix: guard against non-string values in frontmatter aliases #377 (quotes / line width).

Verified in Obsidian with the repro notes from #354 (aliases: [null, "TestAlias"], aliases: 42, and the trailing-colon YAML template): no crash, filtering narrows correctly, and normal alias search is unaffected. npm test passes (190/190).

Related issue

Follow-up to #377. Related: #354.

Type of change

• Bug fix
• New feature
• Documentation
• Refactor
• Other

Checklist

• npm run lint passes ("Use sentence case for UI text" errors are acceptable for brand names)
• npm run build passes
• Tested in Obsidian
• Existing functionality still works
• Documentation updated if needed

Testing environment

• Agent: N/A (the change only affects the @-mention search path; no agent connection involved)
• OS: macOS

Screenshots

N/A

Summary by CodeRabbit

• Bug Fixes
  • Improved note search and metadata handling for aliases.
  • Consistently excludes malformed, empty, or unsupported alias values.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: f904aea6-990e-4df8-bb5f-c25816164bbb

📥 Commits

Reviewing files that changed from the base of the PR and between 9266e15 and 0bc2a98.

📒 Files selected for processing (1)

• src/services/vault-service.ts

🚧 Files skipped from review as they are similar to previous changes (1)

• src/services/vault-service.ts

---

📝 Walkthrough

Walkthrough

This PR adds a shared helper to normalize frontmatter aliases. Note search and metadata conversion now use the same logic. Non-string and empty-string aliases are excluded.

Changes

Alias normalization flow

Layer / File(s)	Summary
Shared alias normalization and usage src/services/vault-service.ts	normalizeFrontmatterAliases converts frontmatter alias values into arrays of non-empty strings. searchNotes uses the helper for fuzzy-search fields. convertToMetadata uses the helper and exposes aliases only when valid strings remain.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• RAIT-09/obsidian-agent-client#377: Both PRs update alias handling in VaultService.searchNotes and convertToMetadata.

Poem

🐇 Clean aliases hop in line,
Empty ones stay behind.
Search and metadata share the trail,
While valid strings never fail.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the primary bug fix: excluding non-string scalar aliases during metadata conversion.
Description check	✅ Passed	The description covers the change, related issues, type, checklist, testing environment, validation results, and screenshots status.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ 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/frontmatter-alias-normalization

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[coderabbitai]

Actionable comments posted: 1

🤖 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/services/vault-service.ts`:
- Around line 127-128: Update the alias normalization logic near the list
construction and string filter so scalar and array inputs apply the same
empty-string rule; if empty aliases are invalid, exclude empty strings from both
forms. Add tests covering aliases supplied as "" and [""] and verify neither
produces an alias or empty search field.

🪄 Autofix

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: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 09fd9c4b-83b8-4550-ab38-0af8b49116b4

📥 Commits

Reviewing files that changed from the base of the PR and between 5d8a1c5 and 9266e15.

📒 Files selected for processing (1)

• src/services/vault-service.ts