Unify previous source resolution

docs/internal/command-restore.md

@@ -43,8 +43,9 @@ Planner behavior:
 For a non-dry-run restore, planning/classification happens only after acquiring
 the session lock. Runner manifest/reuse checks acquire that same lock first.
 
-Previous-cache files are planned separately through `previouscache.BuildPlan`
-when configured previous-session requirements exist.
+Previous-cache readiness is resolved through `previouscache.Resolve` for restore,
+prepare, status, and validation. A committed source is selected only by its
+exact source identity; legacy fallback remains isolated and rejects ambiguity.
 
 ## Execution Contract
 
@@ -56,6 +57,9 @@ Execution order and safety:
 - manifest replacement is validated before rename;
 - each committed object is verified against its declared checksum, size, and
   generation before installation;
+- a committed manifest already verified during discovery is retained for the
+  matching restore action and revalidated before installation, avoiding a
+  second body transfer;
 - failed installs do not roll back files already written in the same execution.
 - a durable `.restore-incomplete.json` marker is written before installation.
   It blocks runners until a restore retry completes all verified installs and
@@ -75,7 +79,8 @@ Audio restore path:
 
 ## Reporting Contract
 
-- dry-run mode prints a summary and performs no local writes;
+- dry-run mode prints a summary, performs no durable session writes, and may
+  read remote current-state or object-identity data to produce that summary;
 - execution mode persists the canonical restore report described in
   [Operations](../operations.md#restore-workflow);
 - report includes plan counts, per-action status, and execution failures.

docs/internal/stage-prepare.md

@@ -34,11 +34,13 @@ Materialize canonical current-session inputs before processing stages.
 - scans enabled configured artifact inputs for `narratio.previous_session.artifact.*` requirements.
 - when previous requirements exist:
   - clears managed `previous/` state;
-  - builds previous-cache remote plan;
+  - resolves the pointer-selected previous source through the shared resolver;
   - downloads previous manifest/artifacts;
   - records previous inputs in `manifest.inputs`.
 
-Required previous-session inputs fail when unavailable; optional missing inputs are skipped.
+Required previous-session inputs fail when unavailable; optional missing inputs
+are typed skipped results. Committed sources use their exact source-to-destination
+mapping, while the isolated legacy reader rejects ambiguous fallback matches.
 
 ## Invariants
 

docs/operations.md

@@ -269,6 +269,10 @@ Apply:
 narratio session restore 2026-04-04
 ```
 
+`--dry-run` does not write durable session files. It still reads the selected
+remote current state and may read object identity/content needed to classify the
+plan, so it is not a network-free operation.
+
 Default restore scope:
 
 - the committed session manifest and the committed transcript/artifact objects

docs/roadmap/implementation.md

@@ -35,7 +35,7 @@ All stages are pending when this plan is created.
 | 17 | Bind restore/status to a committed snapshot and reject conflicts | COR-008, COR-009, TST-005 | Completed |
 | 18 | Serialize restore transitions and make restored paths portable | RSK-006, RSK-008 | Completed |
 | 19 | Bind audio cache reuse to remote object identity | RSK-007 | Completed |
-| 20 | Unify previous-source readiness and eliminate duplicate transfers | COR-010, EFF-001 | Pending |
+| 20 | Unify previous-source readiness and eliminate duplicate transfers | COR-010, EFF-001 | Completed |
 | 21 | Tighten configuration parsing, values, and expectations | COR-012–COR-015, TST-011, TST-014 | Pending |
 | 22 | Make product configuration truthful and own remote temp files | COR-024, RSK-009, ARC-004 | Pending |
 | 23 | Stream WhisperX uploads and make the adapter race-safe | COR-016, EFF-002, TST-001 | Pending |