Keep transcript sections fixed throughout processing

docs/roadmap/implementation.md

@@ -525,6 +525,15 @@ required validation.
 
 ## Stage 5 — Fix Chunk Boundaries for the Entire Run
 
+**Completed 2026-09-24.** The runner now partitions once before the module loop,
+returns the initial section inventory, applies approved corrections only inside
+their identified sections, carries current text forward, and recombines the
+transcript after processing. Tests cover substantial text growth, stable segment
+membership, empty work, and impossible chunk constraints. `go test
+./internal/core/chunking` and `git diff --check` passed. Runner tests remain
+unavailable because warning-field consumers still fail compilation; Stage 6
+replaces them with operation outcomes.
+
 **Work:** Move the runner's chunking call before its stage loop. Own fixed chunk
 states and initial inventory in runner output. Execute each module using the current
 text of those same chunks, and apply fully approved candidates only within their