feature-boundary-planner

<!-- Adapted for codexhost from ZCode 872ad960de7ec172591f7e1952f7849229f94521. See ../NOTICE.md for provenance and licenses. --> # Feature boundary planner Choose the scope implied by the request: **impact-only** reads and reports; **planning** establishes behavior and acceptance cases; **implementation-handoff** identifies concrete code and validation work. Respect existing user decisions and preserve unrelated work. ## Trace the current implementation 1. Use [source discovery](references/source-discovery.md) and the repository documentation index to locate the relevant current contracts and entrypoints. Verify paths and symbols in this checkout. 2. Classify the change as presentation, option source, draft/default, validation, command effect, persistence, or recovery. 3. Trace each affected surface to its authoritative owner: Renderer/Desktop binding → Host request routing → Adapter/native operation → confirmed event → projection. Some features end earlier; follow only the relevant path. 4. Use `$dep-refs` for callers and re-exports. Imports alone do not prove a product dependency. Start with direct relationships, expanding when ownership or a caller remains unresolved. 5. Distinguish official Codex Threads from external Harness Threads; local and remote Hosts; Native Session facts from Host metadata; capabilities from UI affordances. Use the repository terminology. For stateful changes, show the event order and owner in a concise diagram. Identify cancellation, duplic...