Found during v0.8.3 release review (End User / Data Engineer persona). Deferred because it needs design + tests for a config flag or heuristic (>30 min).

Context

v0.8.3 added a REQUIRED "Investigate before drafting" section to packages/opencode/src/session/prompt/plan.txt mandating at least one read-only tool call before the plan agent drafts. There's a prose escape hatch for trivial tasks (broadened in v0.8.3 to cover single well-specified edits to already-read files), but it relies on the model's judgment of the prose — a literal-minded compliant model (the exact class this targets) may still grep on a one-line rename, adding a 3-5s round trip and chattier output every time.

Suggested fix

A deterministic trivial-plan fast-path — a config flag or a heuristic — so single-edit / fully-specified plans skip the exploration mandate without relying on the model interpreting the prose escape hatch. Pair with telemetry on how often the explore-first mandate adds a tool call to previously-trivial sessions (latency/token cost on the easy case).

Scope

packages/opencode/src/session/prompt/plan.txt, plan-agent loop in packages/opencode/src/session/prompt.ts, plus a config surface.