fix: register sisyphus-junior as builtin agent

[rluisr]

Summary

• Register Sisyphus-Junior as a proper builtin agent across type system, agent sources, barrel exports, and model fallback requirements
• Fixes [Bug]: Sisyphus-Junior agent not registered - category delegation fails completely #1697

Changes

• src/config/schema/agent-names.ts: Add "sisyphus-junior" to BuiltinAgentNameSchema
• src/agents/types.ts: Add "sisyphus-junior" to BuiltinAgentName type union
• src/agents/builtin-agents.ts: Import factory and add to agentSources map (for builtinAgentNames Set correctness)
• src/agents/builtin-agents/general-agents.ts: Skip in collectPendingBuiltinAgents (handled separately via agent-config-handler.ts, same pattern as atlas)
• src/agents/index.ts: Add barrel export for createSisyphusJuniorAgentWithOverrides and SISYPHUS_JUNIOR_DEFAULTS
• src/shared/model-requirements.ts: Add AGENT_MODEL_REQUIREMENTS["sisyphus-junior"] with fallback chain (claude-sonnet-4-6 -> gpt-5.4 -> gemini-3-flash) for model-fallback hook and doctor checks

Testing

bun test src/config/schema.test.ts src/agents/sisyphus-junior/index.test.ts src/tools/delegate-task/tools.test.ts src/tools/delegate-task/category-resolver.test.ts src/plugin-handlers/config-handler.test.ts

All 251 tests pass.

Related Issues

Closes #1697

---

Summary by cubic

Register sisyphus-junior as a builtin agent so types, exports, and model fallback work consistently across the app. Restores correct fallback behavior and fixes type mismatches (fixes #1697).

• Bug Fixes
  • Added sisyphus-junior to BuiltinAgentName schema and type.
  • Wired into agentSources and barrel exports.
  • Excluded from collectPendingBuiltinAgents (handled via config handler, like atlas).
  • Defined fallback chain: claude-sonnet-4-6 → gpt-5.4 (medium) → gemini-3-flash.
  • Updated model-requirements test to expect 11 builtin agents including sisyphus-junior.

^{Written for commit 123f73c. Summary will update on new commits.}

[github-actions]

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

[rluisr]

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

[cubic-dev-ai]

No issues found across 6 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Auto-approved: This PR follows the established pattern for registering builtin agents, adds necessary types and schemas, and passes all relevant tests without altering existing agent logic.}

[acamq]

The PR correctly adds sisyphus-junior as a builtin agent across the type system and model fallback, but the test suite wasn't updated to reflect this change.

Issue

Test: src/shared/model-requirements.test.ts
Line: 213
Error:

Expected length: 10
Received length: 11

The test "all 10 builtin agents have valid fallbackChain arrays" expects exactly 10 agents, but AGENT_MODEL_REQUIREMENTS now has 11 entries after adding sisyphus-junior.

Fix Required

Update src/shared/model-requirements.test.ts (lines 194-213):

test("all 11 builtin agents have valid fallbackChain arrays", () => {
  // #given - list of 11 agent names
  const expectedAgents = [
    "sisyphus",
    "hephaestus",
    "oracle",
    "librarian",
    "explore",
    "multimodal-looker",
    "prometheus",
    "metis",
    "momus",
    "atlas",
    "sisyphus-junior",  // ← Add this line
  ]

  // when - checking AGENT_MODEL_REQUIREMENTS
  const definedAgents = Object.keys(AGENT_MODEL_REQUIREMENTS)

  // #then - all agents present with valid fallbackChain
  expect(definedAgents).toHaveLength(11)  // ← Change from 10 to 11
  for (const agent of expectedAgents) {
    // ... rest of test unchanged

Changes Summary

1. Add "sisyphus-junior" to expectedAgents array (line 207)
2. Change test description from "all 10" to "all 11" (line 194)
3. Update assertion from toHaveLength(10) to toHaveLength(11) (line 213)

---

Note: The author mentioned "All 251 tests pass" in the PR description, but CI shows this test failing. Likely a local test vs CI environment difference.

[acamq]

Once you fix the test, this PR is good to merge.

[rluisr]

@acamq fixed