Summary

Fixes #11461

agents.defaults.subagents.model is ignored when spawning isolated cron sessions. All isolated sessions fall back to agents.defaults.model.primary, regardless of the subagents config. This means users can't use cheaper local models (e.g. Ollama) for background cron work while keeping premium models for interactive sessions.

lobster-biscuit

Repro Steps

1. Configure agents.defaults.subagents.model to a different model than the main agent model:

   {
     "agents": {
       "defaults": {
         "model": { "primary": "anthropic/claude-sonnet-4-5" },
         "subagents": { "model": "ollama/llama3.2:3b" }
       }
     }
   }

2. Create a cron job with sessionTarget: "isolated" (no explicit --model)
3. Run the job
4. Observe the session uses anthropic/claude-sonnet-4-5 instead of ollama/llama3.2:3b

Root Cause

In src/cron/isolated-agent/run.ts, resolveConfiguredModelRef() only checks cfg.agents.defaults.model.primary and never checks cfg.agents.defaults.subagents.model. The correct pattern already exists in sessions-spawn-tool.ts which properly resolves subagent models.

Behavior Changes

• Isolated cron sessions now respect agents.defaults.subagents.model (and per-agent subagents.model) when selecting the default model.
• Precedence chain: explicit job model > gmail hook model > subagents.model > main model.
• No change when subagents.model is not configured (falls back to main model as before).
• Extracted normalizeModelSelection from sessions-spawn-tool.ts into shared model-selection.ts to avoid duplication.

Codebase and GitHub Search

• Searched sessions-spawn-tool.ts for reference implementation of subagent model resolution.
• Verified resolveConfiguredModelRef only checks agents.defaults.model, confirmed the gap.
• Confirmed no existing PRs targeting [Bug]: agents.defaults.subagents.model config ignored in cron isolated sessions #11461.

Tests

• 4 new integration tests (isolated-agent.subagent-model.test.ts):
  • Uses subagents.model when set (string format)
  • Explicit job model override takes precedence over subagents.model
  • Falls back to main model when subagents.model is unset
  • Supports {primary} object format for subagents.model
• 5 new unit tests (model-selection.test.ts): normalizeModelSelection utility coverage
• All 963 test files / 6523 tests pass

Manual Testing

N/A — fully covered by automated tests.

Sign-Off

• Models used: Claude (AI-assisted)
• Submitter effort: read issue, traced code, implemented fix + tests, ran full gate
• Agent notes: The fix mirrors the existing sessions-spawn-tool.ts pattern. normalizeModelSelection was extracted to a shared module to avoid duplication.

Made with Cursor

Greptile Overview

Greptile Summary

This change fixes isolated cron sessions to respect agents.defaults.subagents.model (and per-agent subagents.model) when choosing the default model, matching the existing behavior in sessions-spawn-tool.ts. To avoid duplication, it extracts normalizeModelSelection into src/agents/model-selection.ts and adds unit + integration coverage for the new resolution behavior.

Confidence Score: 3/5

• This PR is close to mergeable but has a model-allowlist enforcement gap in cron isolated sessions.
• Core change is small and well-tested, but the new subagents.model resolution path in runCronIsolatedAgentTurn does not enforce the model allowlist in the way the explicit job override does, which can lead to running disallowed models in allowlist configurations.
• src/cron/isolated-agent/run.ts

Context used:

• Context from dashboard - CLAUDE.md (source)
• Context from dashboard - AGENTS.md (source)