Protect initial pipeline stage resume semantics

docs/operations.md

@@ -88,7 +88,9 @@ Canonical stage order:
 
 Execution rules:
 
-- succeeded stages are skipped unless `--force` is set;
+- succeeded stages are skipped unless `--force` is set; stages with semantic
+  configuration contracts additionally require matching versioned evidence,
+  and missing legacy evidence causes a safe one-time rerun;
 - `run` continues interrupted or partially completed sessions by running non-succeeded stages;
 - forcing a stage marks succeeded transitive dependents as `stale` before the
   replacement runs; render and extract are independent siblings; and
@@ -97,6 +99,15 @@ Execution rules:
   repeated self-skip with the same reason and no outputs is stable and does not
   perpetually rerun dependent work.
 
+Prepare, transcribe, and merge currently provide semantic-configuration
+evidence. Changing prepare selection semantics reruns all fixed descendants;
+changing WhisperX language/service identity reuses prepare; and changing a
+Seriatim merge transformation reuses prepare and transcribe. Operational
+timeouts, retry/concurrency tuning, executable paths, workspace/cache/spool
+placement, reports, diagnostics, and secret values are excluded. Configuration,
+models, prompts, modules, or resources loaded privately inside external tools
+remain unobservable to Narratio and require an explicit `--force` after change.
+
 An explicit self-skip is a durable `skipped` stage outcome that later runs
 reconsider. It differs from successful no-output execution: disabled `render`
 and `publish`, and absent or no-executable `analyze`, record `succeeded` with