Permit safe cross-run output declarations

docs/internal/artifacts.md

@@ -249,6 +249,12 @@ New publication creates run-scoped immutable objects, including
 mutable selector is `current/commit-pointer.json`; readers verify its selected
 commit and declared object generations/checksums.
 
+A `published_output` declaration may identify its commit's run or an earlier
+immutable run in the same campaign/session namespace. The key parser validates
+that namespace, rejects mutable and malformed keys, and derives the originating
+run from the exact declaration. All other commit artifacts remain confined to
+the commit's own run prefix.
+
 Campaign, session, and Narratio run IDs are validated as portable opaque
 segments at configuration and artifact boundaries before they can be used in a
 workspace or S3 namespace. Previous-artifact destinations remain typed,

docs/operations.md

@@ -387,6 +387,12 @@ commit by version, checksum, size, and storage generation; committed artifacts
 are also checksum- and generation-bound. Readers accept this contract now and
 strictly reject mismatched or unknown data.
 
+A selected commit may carry a `published_output` declaration from an earlier
+run in the same campaign/session. Restore, previous-session caching, status,
+and artifact inspection use that declaration's exact immutable key and stable
+source; they do not reconstruct a current-run key or scan the session prefix.
+Other artifact types remain confined to the selected commit's own run.
+
 When the pointer is absent, remote state is not published; republish the
 session to establish a committed snapshot. Remote commit state does not carry
 local `current_pointer_written` metadata.

docs/roadmap/implementation.md

@@ -140,7 +140,7 @@ and removal. Run `go test ./internal/artifacts ./internal/adapters/storage` and
 
 ## Stage 3 — Permit Safe Cross-Run Declarations
 
-**Status:** Pending
+**Status:** Completed
 
 ### Goal