Reject unknown Edge run agentId instead of falling back to the default adapter

[DeliciousBuding]

Summary

POST /v1/runs accepts an optional agentId that is documented as the requested Agent Runtime adapter. When that agentId is unknown or not registered, the executor silently keeps using its default adapter instead of failing the run. That makes an explicit runtime selection unreliable.

Evidence

• api/openapi.yaml:1812-1814 documents agentId as the adapter ID (claude-code, codex, opencode, orchestrator) and says only an omitted value defaults to the server default.
• edge-server/internal/api/handlers.go:460-472 parses agentId, and edge-server/internal/api/handlers.go:534-546 passes it into RunProcessContext without validating it against AdapterRegistry before creating and accepting the run.
• edge-server/internal/adapters/registry.go:76-90 correctly returns an error when a non-empty agentID is not registered.
• edge-server/internal/lifecycle/process_executor.go:248-254 discards that error: it initializes adapter := e.adapter, calls Resolve(runCtx.AgentID), and only replaces the adapter if err == nil. On error, execution proceeds with the default adapter.

Impact

A caller can request a specific runtime and get a successful 202 Accepted, but the process may run under a different runtime. Examples:

• Requesting codex on an Edge configured only with claude-code can run Claude Code instead of failing.
• A typo or stale agentId silently changes model/tool/permission behavior.
• Product UI and Hub dispatch cannot reliably interpret the run as the adapter the user selected.

This is especially important because adapters have different permission flags, sandbox behavior, session-resume semantics, streaming formats, and model resolution.

Suggested fix

• Validate non-empty agentId before creating the run, or make ProcessExecutor.Start return the registry resolution error before launching a process.
• Return a clear 400/404-style error such as agent_adapter_not_found for an unknown explicit adapter.
• Keep default adapter fallback only for omitted agentId.
• Add tests for explicit known adapter, omitted adapter defaulting, and explicit unknown adapter rejection.

Acceptance criteria

• Unknown non-empty agentId cannot launch any process under the default adapter.
• The API response distinguishes omitted default selection from invalid explicit selection.
• Tests cover POST /v1/runs and executor-level adapter resolution behavior.

[DeliciousBuding]

Fixed in B1-B5 security audit batches + Johnny Phase 0-8 Hub features + Edge-Hub Bridge (2026-05-25)