diff --git a/docs/agents/CONTAINER-NOTES.md b/docs/agents/CONTAINER-NOTES.md
index 7d8dae19..dc4a5b95 100644
--- a/docs/agents/CONTAINER-NOTES.md
+++ b/docs/agents/CONTAINER-NOTES.md
@@ -118,7 +118,19 @@ python3 tools/re-capture/gmem.py find hex:820af844 400
 ## Verifying your own work
 
 * Reborn's disc-gated tests **self-skip** without `SYLPHEED_DISC`. A green run
-  with it unset means almost nothing. `build-reborn test` wires it up for you.
+  with it unset means almost nothing.
+  🔴 **But `build-reborn` does not work in this container (2026-08-29).** Line 15
+  is `SRC="${PROJECT_DIR:-/work}/Syplheed-Reborn"` — note the transposed letters —
+  and no such directory exists; the workspace is at **`/work`** itself. It fails
+  immediately with `cd: /work/Syplheed-Reborn: No such file or directory`, so the
+  documented way to run the disc-gated tests is broken.
+  ✅ **Run them directly instead**, setting the variable yourself:
+  ```bash
+  SYLPHEED_DISC=/disc cargo test -p sylpheed-formats --test <name>
+  ```
+  ⚠️ This is the **second** wrapper in this container pointing at a source root
+  that does not exist — `build-canary` has the same defect. Check a wrapper's
+  `SRC` before trusting that a green or a failure came from your code.
 * Prefer a headless self-verify over "it compiles": `sylpheed-cli mesh render`,
   `screen render`, `save info` all produce checkable artifacts.
 * A Bevy system-parameter conflict is invisible to the type checker and panics