fix: include user/project agents in task(subagent_type) resolution

[trafgals]

Summary

Re-implements the functionality from closed PR #2690 to make user-defined and project-defined agents callable via task(subagent_type=...).

Problem

The original PR #2690 attempted to allow user agents (from ~/.config/opencode/agents/) and project agents (from .claude/agents/) to be callable via task(subagent_type="my-agent"). However, the branch became incompatible with dev due to ongoing refactoring while the PR was open.

Solution

This PR re-implements the feature against current upstream/dev:

• Import loadUserAgents and loadProjectAgents from claude-code-agent-loader
• Merge user/project agents with server agents in resolveSubagentExecution()
• Server agents take precedence on name collisions
• Primary-mode agents from user/project are filtered out

Changes

• src/tools/delegate-task/subagent-resolver.ts: Added agent merging logic
• src/tools/delegate-task/subagent-resolver.test.ts: Added 4 new test cases

Test Results

All 17 tests pass (13 existing + 4 new):

• User agent resolution from loadUserAgents()
• Project agent resolution from loadProjectAgents()
• Server agent precedence over user/project agents with same name
• Primary-mode agents correctly filtered out

---

Summary by cubic

Enable task(subagent_type=...) to resolve user and project agents. We merge user (~/.config/opencode/agents/) and project (.claude/agents/) agents with server agents; server wins, project overrides user; ignore primary agents.

• Bug Fixes

  • Resolve user/project agents via loadUserAgents/loadProjectAgents in resolveSubagentExecution(); enforce server > project > user; filter primary; resolve models.
  • Add 5 tests covering user agent, project agent, server precedence, project-overrides-user, and primary filtering.

• Refactors

  • Switch tests to use spyOn for agent loader mocks instead of vi.mock (bun:test best practice).

^{Written for commit 5441c84. Summary will update on new commits.}

[github-actions]

All contributors have signed the CLA. Thank you! ✅
_{Posted by the CLA Assistant Lite bot.}

[cubic-dev-ai]

1 issue found across 2 files

Confidence score: 3/5

• There is a concrete behavior risk in src/tools/delegate-task/subagent-resolver.ts: same-named project agents are not overriding user agents, so task(subagent_type=...) can resolve the wrong target in shadowing repositories.
• Given the 6/10 severity with high confidence (9/10), this is more than a cosmetic issue and could cause user-visible misrouting of delegated tasks, so merge risk is moderate rather than minimal.
• Pay close attention to src/tools/delegate-task/subagent-resolver.ts - merge-order precedence needs to ensure project agents win over same-named user agents.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/tools/delegate-task/subagent-resolver.ts">

<violation number="1" location="src/tools/delegate-task/subagent-resolver.ts:95">
P2: Project agents should override same-named user agents here; the current merge order makes `task(subagent_type=...)` resolve the wrong agent in repositories that shadow a global agent.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

1 issue found across 3 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/tools/delegate-task/subagent-resolver.test.ts">

<violation number="1" location="src/tools/delegate-task/subagent-resolver.test.ts:652">
P2: This test doesn’t actually verify project-over-user precedence. Both candidates are named `my-custom-agent`, and the only assertion checks the shared name, so the test will pass even if the resolver picks the user agent. Add an assertion on a distinguishing field (like the resolved model) to make the precedence check meaningful.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

0 issues found across 2 files (changes from recent commits).

_{Auto-approved: Logic correctly implements agent precedence (Server > Project > User) and case-insensitive matching, matching existing behavior while adding tested support for local agents.}

[trafgals]

I have read the CLA Document and I hereby sign the CLA

[trafgals]

I have read the CLA Document and I hereby sign the CLA

[code-yeongyu]

QA Results

Tests: 18 pass, 0 fail (bun test src/tools/delegate-task/subagent-resolver.test.ts)

All 18 tests pass including the 4 new test cases:

• User agent resolution from loadUserAgents()
• Project agent resolution from loadProjectAgents()
• Server agent precedence over user/project agents with same name
• Primary-mode agents correctly filtered out

Code review notes:

• The bun.lock diff bumps all platform binaries from 3.11.0 → 3.14.0 which is noisy but harmless (rebased on newer dev)
• Agent merging logic with proper precedence (server > project > user) is clean
• Case-insensitive matching via .toLowerCase() is a nice touch

One minor concern: this PR uses vi.mock (vitest syntax) in bun:test. It works in bun but isn't idiomatic — the rest of the test suite uses spyOn. Not a blocker.

[cubic-dev-ai]

0 issues found across 1 file (changes from recent commits).

_{Requires human review: Logic for agent merging is sound, but the bun.lock update includes binary dependency bumps (3.11 to 3.14) which cannot be guaranteed 100% regression-free without further context.}