Preflight and publish required outputs through an output session

docs/roadmap/implementation.md

@@ -679,6 +679,16 @@ truth as the structured output.
 
 ## Stage 10 — Implement Required Output Initialization and Finalization
 
+**Completed 2026-09-24.** A filesystem output session now checks active
+destination collisions (including symlink and hardlink aliases), preflights the
+transcript without truncation, initializes all enabled report files, and replaces
+final files through owned temporary files. It attempts every report after a
+finalization error and makes one failed-status pass while retaining any published
+transcript. Temporary-directory tests cover collisions, unavailable parents,
+disabled reporting, stdout mode, overwrite/permissions, initialization failure,
+and partial finalization. `go test ./internal/core/diagnostics` and
+`git diff --check` passed. CLI sequencing remains for Stage 12.
+
 **Work:** Add the output-session filesystem adapter described in G. Resolve active
 paths, protect collisions before truncation, preflight transcript writes without
 destroying existing content, initialize all enabled reports, and publish final files