diff --git a/.env.example b/.env.example
index 69e1c1a3b0..92065948e9 100644
--- a/.env.example
+++ b/.env.example
@@ -1962,6 +1962,12 @@ APP_LOG_TO_FILE=true
 # Default: 8000 (8 seconds). On timeout, a last-good 200 is served when available.
 # CATALOG_BUILD_TIMEOUT_MS=8000
 
+# Age after which a connection's synced model list stops being authoritative for routing (#12849).
+# A stale (or never-timestamped) synced catalog fails open to the provider registry.
+# Used by: src/lib/db/models/activeSyncedCatalog.ts
+# Default: 2592000000 (30 days)
+# OMNIROUTE_SYNCED_CATALOG_STALE_AFTER_MS=2592000000
+
 # ── NanoBanana (Image Generation) ──
 # Polling config for async image generation jobs.
 # Used by: open-sse/handlers/imageGeneration.ts
diff --git a/changelog.d/maintenance/12732-env-synced-catalog-stale-after.md b/changelog.d/maintenance/12732-env-synced-catalog-stale-after.md
new file mode 100644
index 0000000000..9a7b6c1ef8
--- /dev/null
+++ b/changelog.d/maintenance/12732-env-synced-catalog-stale-after.md
@@ -0,0 +1 @@
+- **docs(env):** document `OMNIROUTE_SYNCED_CATALOG_STALE_AFTER_MS` (#12849, default 30 days) in `.env.example` and `ENVIRONMENT.md`; the stale-synced-catalog fail-open shipped the override without either, which the env/docs contract gate reports as code-only ([#12732](https://github.com/diegosouzapw/OmniRoute/issues/12732))
diff --git a/docs/reference/ENVIRONMENT.md b/docs/reference/ENVIRONMENT.md
index 83ceb71568..be26a0282a 100644
--- a/docs/reference/ENVIRONMENT.md
+++ b/docs/reference/ENVIRONMENT.md
@@ -1053,6 +1053,7 @@ desktop install.
 | `OPENROUTER_CATALOG_TTL_MS`                    | `86400000` (24h)                       | `src/lib/catalog/openrouterCatalog.ts`                                             | OpenRouter model catalog cache TTL.                                                                         |
 | `MODEL_CATALOG_INCLUDE_NAMES`                  | `true`                                 | `src/shared/constants/featureFlagDefinitions.ts`                                   | Include display-friendly `name` fields in `/v1/models` responses. Disable for clients that expect IDs only. |
 | `CATALOG_BUILD_TIMEOUT_MS`                     | `8000` (8s)                            | `src/app/api/v1/models/catalogCache.ts`                                            | Cold-path wait bound for a coalesced `GET /v1/models` catalog rebuild (#12627). On timeout, a last-good 200 is served when one exists. |
+| `OMNIROUTE_SYNCED_CATALOG_STALE_AFTER_MS`      | `2592000000` (30 days)                 | `src/lib/db/models/activeSyncedCatalog.ts`                                         | Age after which a connection's synced model list stops being authoritative for routing and fails open to the registry (#12849). Never-timestamped rows count as stale. |
 | `NANOBANANA_POLL_TIMEOUT_MS`                   | `120000`                               | `open-sse/handlers/imageGeneration.ts`                                             | Max wait for NanoBanana image generation jobs.                                                              |
 | `NANOBANANA_POLL_INTERVAL_MS`                  | `2500`                                 | `open-sse/handlers/imageGeneration.ts`                                             | NanoBanana job polling frequency.                                                                           |
 | `ADOBE_FIREFLY_SUBMIT_BASE_DELAY_MS`           | `8000`                                 | `open-sse/services/adobeFireflyUpscale.ts`                                         | Base delay for the Adobe Firefly upscale submit-retry exponential backoff.                                  |