fix(core): a file renamed just as its create lands keeps its access (B174)

docs/BUGS.md

@@ -12,6 +12,27 @@ Conventions:
 
 ---
 
+## B174 — A file renamed just as its create lands is refused with "Permission denied"
+
+**Status:** Fixed (unverified).
+**Found:** 2026-10-04, by the simulation suite on 378667f (`one_client_on_a_good_link`, seed 6):
+`rename c.bin -> b.txt` answered `EACCES` right after a settle. Not reproduced in three replays.
+
+**Where:** `Db::effective_node_access` in `crates/pdfs-core/src/db/share_access.rs`.
+
+**Cause.** Every change on the mount first asks whether the node may be written, and a node
+with no row is refused. When a create lands, its row takes the uid Drive gave it before the
+tree does (B173's gap). A rename in between asked by the stand-in the tree still had, found no
+row under it, and was refused.
+
+**Fix.** A stand-in is looked up by its local id, so it finds its row before and after the
+create lands.
+
+**Test:** `a_stand_in_keeps_its_access_once_its_create_has_landed` in
+`crates/pdfs-core/src/db/tests.rs`.
+
+---
+
 ## B173 — A file deleted just as its create lands stays on Drive
 
 **Status:** Fixed (unverified).

docs/CHANGELOG.md

@@ -74,6 +74,8 @@ by its local id, in the queue, the stored tree and pins alike.
   longer waits for the upload's next retry (B171).
 - **A file deleted just as it reached Drive is removed from Drive too.** It no longer stayed
   there, and the next file with that name no longer became a conflict copy (B173).
+- **Renaming a file just as it reaches Drive no longer fails with "Permission denied"**
+  (B174).
 - **A file renamed just as its upload finished keeps its new name.** The mount no longer showed
   the old name, and a second rename no longer failed with "No such file or directory" (B152,
   B172).

docs/MILESTONE-3.0.0-STATUS.md

@@ -9,7 +9,7 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
 - **Phase 2**: local ids, inode = local id, one tree for every mount (2.10.0).
 - **Phase 3, first part**: mkdir, create, rename, unlink and rmdir on the mount are recorded
   locally and sent from the queue; `"local_first": false` brings back the old path (5e0f30c).
-- Fixes from the simulation and account runs since then: B127 and B141 to B173.
+- Fixes from the simulation and account runs since then: B127 and B141 to B174.
 - **Sync issues, first cut** (§6.2): refusals sorted into issues, shown at once in the app,
   tray and CLI; Export button and `pdfs sync export`; `pdfs sync issues`.
 
@@ -117,7 +117,8 @@ Tracks `docs/MILESTONE-3.0.0.md`. Update it with every commit that moves a phase
          fixed). Run three at a time on 2502af6, seed 8 failed two of nine runs: a file renamed
          while its upload was read back showed its old name again (B172, fixed). The loop
          on d850265 failed seed 12 once in nine runs: a file deleted just as its create
-         landed stayed on Drive (B173, fixed).
+         landed stayed on Drive (B173, fixed). The suite on 378667f failed seed 6: a rename
+         in the same gap was refused with `EACCES` (B174, fixed).
 5. **Release**: 2.10.0 is tagged; the 2.9.0 tag still waits for the user's go-ahead.
 
 ## After 3.0.0