Fix Add Index functionality

[jsbattig]

Bug Description

The "Add Index" functionality in the Golden Repos admin UI only offers "Semantic + FTS" as a combined option. Users cannot add Semantic or FTS indexes independently. When a repo already has FTS (but not Semantic), selecting "Semantic + FTS" errors because FTS already exists.

Environment

• Version: $(git describe --tags --always 2>/dev/null || echo "current")
• OS: Linux
• Component: CIDX Server Web UI - Golden Repos management page
• Discovered In: stepscommand repo (has FTS only, needed to add Semantic)

Steps to Reproduce

1. Have a golden repo with FTS index only (no Semantic) - e.g., stepscommand repo
2. Navigate to Golden Repos admin page
3. Click "Details" to expand the repo
4. Click "Add Index" button
5. Observe: Only "Semantic + FTS" option is available (no "Semantic only" option)
6. Select "Semantic + FTS" and click Submit
7. Error occurs because FTS already exists

Expected Behavior

• Should be able to add Semantic, FTS, Temporal, and SCIP indexes independently
• Should be able to rebuild/recreate existing indexes
• Should be able to select multiple indexes to create at once
• Confirmation dialog should warn differently when rebuilding vs creating new

Actual Behavior

• Only combined "Semantic + FTS" option exists
• Cannot add Semantic alone when FTS exists
• Cannot rebuild existing indexes (blocked by _index_exists() check)
• No granular control over individual index types

Error Messages / Logs

ValueError: Index type 'semantic_fts' already exists for golden repo 'stepscommand'

(Error occurs in golden_repo_manager.py line 1806-1808 when FTS exists but Semantic doesn't)

Impact Assessment

Severity: High - Blocks core admin workflow
Affected Users: All admins managing golden repositories
Frequency: Every time user needs to add a single index type when partial indexes exist
Workaround: None - cannot add missing index independently through UI

Root Cause Analysis

UI Layer (golden_repos_list.html:178-181)

{% if not (repo.has_semantic and repo.has_fts) %}
<option value="semantic_fts">Semantic + FTS</option>
{% endif %}

Only offers combined option, no individual Semantic or FTS choices.

Backend Layer (golden_repo_manager.py)

1. Valid types restricted (line 1797):

valid_index_types = ["semantic_fts", "temporal", "scip"]

2. Existence check blocks rebuild (line 1805-1808):

if self._index_exists(golden_repo, index_type):
    raise ValueError(f"Index type '{index_type}' already exists...")

3. _index_exists() uses AND logic (line 1927-1946):
   Returns True only when BOTH semantic AND FTS exist, but error is thrown when either exists during creation.

4. Combined creation (line 1824-1825):

if index_type == "semantic_fts":
    command = ["cidx", "index", "--fts"]  # Creates BOTH indexes

Affected Files

• src/code_indexer/server/web/templates/partials/golden_repos_list.html - UI dropdown
• src/code_indexer/server/web/static/js/golden_repo_indexes.js - JS submission logic
• src/code_indexer/server/repositories/golden_repo_manager.py - Backend validation and creation
• src/code_indexer/server/app.py - AddIndexRequest model, valid_index_types validation

Fix Implementation

Changes Required

1. Backend (golden_repo_manager.py)

• Change valid index types to: ["semantic", "fts", "temporal", "scip"]
• Remove semantic_fts combined type entirely (no backwards compatibility)
• Update CLI command mapping:
  • semantic -> cidx index (no --fts flag)
  • fts -> cidx index --rebuild-fts-index
  • temporal -> cidx index --index-commits ...
  • scip -> cidx scip generate
• Remove _index_exists() blocker - allow rebuilding
• Support multiple index types per request (List instead of single string)

2. API (app.py)

• Update AddIndexRequest model to accept index_types: List[str]
• Update valid_index_types validation

3. UI (golden_repos_list.html)

• Replace dropdown with multi-select checkboxes
• Always show all 4 options: Semantic, FTS, Temporal, SCIP
• Indicate existing indexes with "(rebuild)" label
• Allow selecting multiple indexes at once

4. JavaScript (golden_repo_indexes.js)

• Update to collect multiple selected checkboxes
• Update confirmation dialog:
  • New indexes: "Add [types] index to repository?"
  • Rebuilds: "This will rebuild the existing [types] index. Continue?"
  • Mixed: Show both clearly
• Update request body to send array: { index_types: [...] }

Testing Required

• Unit tests for new index types validation
• Unit tests for multi-select request handling
• Integration tests for each index type creation
• E2E test: Add semantic when FTS exists
• E2E test: Rebuild existing index
• E2E test: Multi-select index creation

Implementation Status

• Core fix implemented
• Tests added and passing
• Code review approved
• Manual testing completed
• Documentation updated
• Regression tests added

Completion: 0/6 tasks complete (0%)

Verification Evidence

[To be added after fix]

---

Reported By: Claude Code
Assigned To: [Unassigned]
Found In: current master branch
Fixed In: [To be updated]

[jsbattig]

Implementation Complete - Workflow Verification

Code Review: APPROVED (with findings)

• Core functionality correctly implemented
• Individual index types (semantic, fts, temporal, scip) work independently
• Rebuild existing indexes is allowed
• Found 1 Critical bug (multi-job polling) - filed as separate issue

Manual E2E Testing: ALL PASS (8/8 tests)

Test	Result
UI shows 4 individual checkboxes	PASS
API accepts 'semantic' type	PASS
API accepts 'fts' type	PASS
API accepts 'temporal' type	PASS
API accepts 'scip' type	PASS
API rejects 'semantic_fts'	PASS
Rebuild existing index works	PASS
Multi-select array format works	PASS

Verified Requirements

• Semantic, FTS, Temporal, SCIP indexes can be added independently
• Existing indexes can be rebuilt (no blocking error)
• Multiple indexes can be selected at once
• UI shows '(rebuild)' indicator for existing indexes

Commit

Implementation included in: 4f0001d6 feat: Epic #3 - CLI modularization, CI/CD integration, and dashboard API metrics