diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..0ef76bc
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1,30 @@
+# Project instructions
+
+## No real data in the repository
+
+Everything committed here — code, tests, comments, docs, sample output — uses
+abstract example values. Never a real chat name, chat id, message id, filename,
+account handle, or archive statistic, including ones taken from a session
+transcript or a live run.
+
+This repository archives a private Telegram chat, so real values name a real
+account and its contents. Once committed they persist in history even after the
+file is edited, and scrubbing them means rewriting history and force-pushing.
+
+Use placeholders instead:
+
+| Kind | Use |
+|---|---|
+| chat username | `mychannel`, `@mychannel` |
+| chat / dialog id | `1234567890` (Bot API form `-1001234567890`) |
+| message id | small round numbers, e.g. `4242` |
+| Telegram file id | `1000000000000000001` and up |
+| remote | `myremote:archive`, or a named backend when the backend matters |
+| filenames | descriptive fakes; keep the property under test (unicode, emoji, length) |
+| counts and sizes | round numbers that are obviously illustrative |
+
+Keep the property a fixture exists to test. A test for multi-byte names still
+needs a multi-byte name — make it an invented one, not a real file's.
+
+Real values from a live run belong in the terminal, and in `plans/`, which is
+git-ignored.
diff --git a/README.md b/README.md
index 77a4df8..0e75887 100644
--- a/README.md
+++ b/README.md
@@ -78,8 +78,8 @@ indexing PikPak root 'mychannel'
 
   ↓ total    26/606 files [=>             ] 617.5 MiB / 79.0 GiB  2.5 MiB/s  8h47m
   ↑ total    24/606 files [=>             ] 598.0 MiB / 79.0 GiB  2.4 MiB/s  8h58m
-  ↓ …3214_4242_1000000000000000001.mp4   [=======>       ]  41.2 MiB / 96.0 MiB  1.8 MiB/s
-  ↑ …3214_4243_1000000000000000002.mp4   ⠹                         uploading 1.9 GiB
+  ↓ …7890_4242_1000000000000000001.mp4   [=======>       ]  41.2 MiB / 96.0 MiB  1.8 MiB/s
+  ↑ …7890_4243_1000000000000000002.mp4   ⠹                         uploading 1.9 GiB
 ```
 
 The two legs are counted separately because they run at different speeds and