feat(cli): chat — read a group's last messages, post one

chat GROUP prints the last ten messages, oldest first (-N, as head -N, or
-n N for another count, paging back past the node's 200), and -m posts one
(- reads it from stdin). The application's construction: every epoch key
from chat_keys_req, a post sealed under the current epoch through the
device subkey and signed with this machine's key on the node, the sender's
name inside the envelope; nothing sent past the node's ciphertext bound.
A stored message is read signature first, then key, then content, and one
that fails is shown as unreadable, never dropped. Not done here: the Tier 2
roster check on the signing device.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/CLAUDE.md b/CLAUDE.md
index d440aed..f68bb05 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1168,6 +1168,7 @@ which pytest also runs when `ANDROID_HOME` is set (`test_android_shell.py`).
 | Remote paths, listing, local names | `client/paths.py`, `client/tree.py`, `client/names.py` | `names.UPLOAD_NAME` is copied from the node's `SAFE_UPLOAD_NAME` |
 | Downloads and uploads | `client/transfers.py`, `client/upload_plan.py` | §5.5; `upload_plan` is shared by `put` and the interactive mode |
 | Search across groups | `commands/search.py` | `search_listed` honoured before the index is asked; one result per content hash |
+| Chat: read and post | `client/chat.py`, `commands/chat.py` | `chatbox` seal/verify; signature before decryption; unreadable shown, never dropped; Tier 2 roster check not done |
 | Deleting files | `client/remove.py`, `commands/rm.py` | §5.4: the uploader's account or the node's operator; the whole run is checked before asking |
 | Interactive mode | `meshbay_cli/tui/` | Textual; names are drawn as text, never markup |
 | Man page | `meshbay_cli/manpage.py` | generated from the parser at build time; `test_manpage.py` |