fix(runtime): don't inherit a foreign model across runtimes (v0.283.0)

[vikasprogrammer]

Found on the first live attachable Codex session (#496), which came up as:

■ {"type":"error","status":400,"error":{"message":
   "The 'opus' model is not supported when using Codex with a ChatGPT account."}}
   opus high · ~/agent-os-data/instapods/agents/codex-scout

The fleet runtime default is model: "opus", codex-scout pins no model of its own, so the launcher handed opus straight to Codex.

Two holes, both mine

1. Aliases weren't caught. The guard added in #483 matched ^claude, so full ids like claude-opus-4-8 were refused — but the bare aliases people actually put in the workspace default (opus, sonnet, haiku, fable) went straight through. Patterns are now word-boundary anchored and cover both directions.

2. Inheritance was never validated — the bigger one. PUT /api/agents/:id/config rejects a foreign model, so I thought the trap was closed. It wasn't: the workspace default spans every runtime, so it cannot be correct for all of them at once, and an agent with no model of its own inherited it silently. No amount of per-agent validation catches that.

resolveRuntimeTuning now takes the runtime and drops a model that runtime can't run, so the session falls back to the CLI's own default — a working run rather than a dead one. Dropping beats erroring here: the workspace default is a fallback, and refusing to launch because a fleet-wide setting doesn't suit one runtime would be the wrong trade.

Verified

alias detection
  codex + opus / sonnet / haiku / fable / claude-opus-4-8 / Opus   rejected ✓
  codex + gpt-5-codex / glm-fast-latest                            accepted
  claude + gpt-5-codex / o3 / codex-mini                           rejected ✓

inheritance (workspace default model=opus — the live setting)
  codex agent, no own model              -> (inherit CLI default)
  claude agent, no own model             -> opus
  codex agent w/ own gpt-5-codex         -> gpt-5-codex
  codex agent w/ stale own model=opus    -> (inherit CLI default)
  no runtime given (back-compat)         -> opus

7 new conformance fixtures pin that matrix so it can't regress. Suite 130 → 137.

🤖 Generated with Claude Code