docs: Added documentation on how to inject messages mid-stream in a session

REPL.md

@@ -214,6 +214,11 @@ with "Nothing to undo" once the session has no more messages to remove.
 > **Requires an active session.** `.undo` is only available when a session is open. Outside a session, conversation
 > history is not tracked in memory, so there is nothing to walk back.
 
+> **Discarding an interrupted response:** If you pressed Ctrl+C during a streaming response (see
+> [Mid-Stream Interruption](Sessions#mid-stream-interruption)), the partial response was saved to the session.
+> Use `.undo` to remove it and restore your original prompt if you want to start fresh rather than continue from the
+> partial output.
+
 Note that `.undo` only modifies the in-memory session state. The append-only `messages.md` log is not affected.
 If you save the session after undoing (via `.save session` or automatic save-on-exit), the saved file will reflect
 the trimmed history.

Sessions.md

@@ -140,3 +140,32 @@ at runtime using the `.set` command or configured in the session's YAML file:
 | `skill_instructions`       | Global `skill_instructions` value       | Custom text for the skill-discovery hint. `null` to reset to the built-in default.                                              |
 
 For more information on the Todo System, see the [Todo System documentation](TODO-System).
+
+# Mid-Stream Interruption
+
+When streaming is enabled and a session is active, pressing **Ctrl+C** during a response interrupts the stream and
+preserves any text the model had already generated. The partial response is saved to the session as the model's last
+turn, and Coyote returns to the prompt so you can continue the conversation.
+
+This lets you redirect the LLM mid-flight without losing the context that led up to the interruption:
+
+1. The model begins generating a response.
+2. You press **Ctrl+C**. The stream stops and Coyote prints `Response interrupted`.
+3. The partial response is saved to the session history.
+4. You type your next message at the normal prompt. The model sees the full conversation history, including the partial
+   response, and your new prompt.
+
+If you want to discard the partial response entirely rather than continuing from it, use [`.undo`](REPL#undo---undo-the-last-exchange)
+to remove the last exchange from the session and restore your original prompt for editing or re-sending.
+
+> **Requires an active session.** Mid-stream interruption only preserves partial responses when a session is open.
+> Without a session, Ctrl+C aborts the response as usual and nothing is saved to history.
+
+> **Ctrl+C before the first token.** If you press Ctrl+C while the spinner is still showing (before any response text has
+> arrived), the request is aborted cleanly and nothing is saved. This is identical behavior to how `Ctrl+C` functions without a session.
+
+> **Ctrl+D is always a hard abort.** Pressing Ctrl+D during streaming discards the partial response regardless of session state and
+> exits the REPL.
+
+> **REPL only.** When running Coyote as a one-shot CLI command (`coyote <prompt>`), Ctrl+C aborts as usual. Mid-stream interruption
+> is a REPL-only feature.