dev/docs/subsystem-migration-status.md

Subsystem Migration Status (2025-10-04)

This tracker documents how each major area of the fork compares against the fresh upstream snapshot in codex-rs/ and whether we plan to reuse the upstream implementation or keep a forked variant living under code-rs/.

Subsystem	Upstream delta summary	Decision	Immediate next steps
Core runtime (core/, exec/, protocol/, apply-patch/)	Upstream added a unified executor module, tool router, and richer MCP hooks. Fork keeps pre-refactor pipeline plus fork-only policy/approval features.	Hybrid — adopt upstream executor/tool router incrementally while preserving fork-only approval flow.	Diff code-rs/core vs codex-rs/core focusing on executor/* and tools/*; design an adapter so forked approval + sandbox policy can plug into the upstream router without copy-pasting.
TUI (tui/)	Upstream reorganised history cells into typed renderers, added status dashboards/tests, and removed the older per-cell module tree. Fork still uses the legacy layout with Code-specific UX.	Fork-primary — keep code-rs/tui as the shipping implementation; cherry-pick upstream status widgets/tests once we add equivalent APIs in code-rs.	Inventory upstream additions (status/*, render/renderable.rs) and file GitHub issues to port features where they unlock tooling (status cards, vt100 snapshots).
CLI (cli/, login/, mcp-*, responses-api-proxy/)	Upstream refreshed auth flows (OAuth helpers in rmcp-client) and expanded MCP tooling; fork adds policy prompts, approval gating.	Hybrid — reuse upstream auth/mcp client improvements by wiring them behind feature flags in code-rs while keeping fork-only prompts.	Prototype re-export of codex-rs/rmcp-client login helpers inside code-rs/login; confirm CLI flag parity before deleting fork copies.
Browser tooling (browser/, TUI browser events)	Upstream still lacks the browser agent; fork-only feature.	Fork-only — retain code-rs/browser and related TUI integrations.	Document browser integration in docs/fork-enhancements.md (already tracked); no upstream merge needed.
App server (app-server, app-server-protocol)	Upstream rewrote message processor to use new executor/tool traits. Fork still references old pipeline.	Monitor — do not adopt until core executor bridge (above) lands; otherwise duplicate effort.	Once the core adapter is ready, revisit to see if we can reuse upstream app-server entirely.
SDK / tooling (sdk/typescript, scripts/*)	Upstream scripts now assume codex-* bins. Fork updated to code-*.	Fork-primary with compatibility fallbacks.	Ensure scripts that read templates (e.g., test-responses.js) load both paths (already updated). Review future upstream changes quarterly.
Build & release tooling (build-fast.sh, nix flakes)	Upstream still targets a single workspace. Fork must handle both.	Fork-only — maintain dual-workspace script.	Keep script in sync with upstream bugfixes manually; add regression tests later.

Last updated 2025-10-04. Update this table whenever a subsystem decision changes or a milestone completes.