chore(release): 0.55.0 — R6 API contract & transaction ownership

VERSION

@@ -1 +1 @@
-0.54.0
+0.55.0

frontend/src/lib/releaseNotes.ts

@@ -14,6 +14,17 @@ export interface ReleaseEntry {
 }
 
 export const RELEASE_NOTES: ReleaseEntry[] = [
+  {
+    version: "0.55.0",
+    date: "2026-07-26",
+    summary:
+      "Internal hardening — every write request is type-checked at the edge, quota accounting and Plex sync hold up cleanly when something fails partway, and a new database-backed test net guards it all. No changes to normal use.",
+    chores: [
+      "API contract: every mutating endpoint (~50) now validates its request body against a typed request model at the edge, replacing scattered hand-written checks. Malformed input is rejected consistently with a clear validation error instead of occasionally causing an internal error, and response status codes were made consistent across modules.",
+      "Transaction correctness: YouTube quota accounting now writes in its own transaction — it stays accurate even if the surrounding job rolls back, and no longer commits a job's partial work early. Plex library sync commits each library as it finishes, so a failure partway through keeps the libraries already mirrored. Existing genre-less Plex rows were normalised.",
+      "Testing: a database-backed integration test lane (an ephemeral Postgres spun up for the test run) now runs in the release gate, covering the transaction behaviour and the Plex genre-less-library fix that the pure-logic tests couldn't reach.",
+    ],
+  },
   {
     version: "0.54.0",
     date: "2026-07-26",