fix: execute tool calls in @ollama streaming pass + utility model guidance

[selfagency]

Changes

#149: Tool calls print as raw JSON instead of executing

Root cause: The streaming pass in handleChatRequest (which runs after the tool loop or when no toolInvocationToken is available) dumped tool calls as JSON markdown instead of executing them.

Fix: When request.toolInvocationToken is available, the streaming pass now executes tool calls via vscode.lm.invokeTool and appends results to the conversation context. The JSON fallback is preserved for when no token is available.

#148: No utility model configured for copilot-utility-small with BYOK

Root cause: VS Code Copilot requires a separate utility model when using a BYOK model as the main agent. Opilot doesn't register a model under copilot-utility-small, so VS Code can't find one.

Fix: Detect the "No utility model" error and surface actionable guidance directing the user to configure github.copilot.chat.utilityModel in settings.

Test Plan

• tsc --noEmit passes
• All 24 test files pass (vitest)
• ultracite check passes with no errors

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
src/extension.ts	13% smaller
.opencode/opencode.json	0% smaller

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

View in Codacy

🟢 Metrics 14 complexity · 0 duplication

Metric	Results
Complexity	14
Duplication	0

View in Codacy

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[codecov]

Codecov Report

❌ Patch coverage is 21.73913% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.39%. Comparing base (c5ba153) to head (234fdd9).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/extension.ts	21.73%	15 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #150      +/-   ##
==========================================
- Coverage   63.68%   63.39%   -0.30%     
==========================================
  Files          24       24              
  Lines        3673     3693      +20     
  Branches      939      944       +5     
==========================================
+ Hits         2339     2341       +2     
- Misses        694      709      +15     
- Partials      640      643       +3     

Flag	Coverage Δ
unittests	63.39% <21.73%> (-0.30%)	⬇️

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