Research and design synthesis

2026-09-30. Local baseline2255f26. Two independent candidates grounded current source and proposed existing-boundary vs feature-owned designs. Chosen shape uses feature-owned approval/worktree/dialog modules, grafting the existing-boundary candidate's current Codex native verdict support and extension of hook-event instead of adding a parallel decision-request API. Existing action registry and keyed VTEs remain authoritative.

Provider facts: Claude official PermissionRequest reference supports hookSpecificOutput.decision behavior allow/deny. Empty output returns to native permission flow. Suggestions are not literal TUI options. Codex installed0.159.1 tagged PermissionRequest source and output parser support the same narrow verdict, rejecting updatedInput/updatedPermissions/interrupt=true. Current engine honors configured timeouts without old3s clamp;125s provider timeout with120s internal waiting permits interaction. Codex trust remains user-owned.

Design alternatives rejected: blind numbered PTY answers for automatic native requests; verdict delivery via replayable audit events; separate broker daemon; storing zoom in server layout; parsing Git's quoted display filenames. Broker ownership protects disconnect, supersede and deadline races. Git NUL porcelain and argv protect unusual names.

Defaults settled from accepted priorities: only Allow once/Deny, no permanent permission updates; main/dirty/live checkout removal refused; closing workspace keeps checkout; command palette reuses actions; literal terminal search; diff describes worktree against HEAD, never per-turn. No interview is needed for environment facts or defaults under the user's instruction to proceed.

Independent cross-judge selected B for module depth/ownership, grafting A native Codex support, hook-event extension and path reservation, and rejected compensating checkout deletion. Scores A/B: approval4.5/4.5, deep interfaces4/5, Store/VTE5/5, removal4.5/3.5, provider evidence5/3.5. Parent agrees with this synthesis.