implemented command history

[riturajFi]

✨ Summary

This PR implements command/message history support for the TUI chat editor.
Users can now recall and reuse previously sent messages using the ↑ / ↓ arrow keys, similar to terminal shells or chat clients like Slack.

This addition enhances usability and continuity by allowing users to:

• Navigate through previously sent messages.
• Edit or resend older messages easily.
• Retain command history across application restarts.

Fixes: #606

---

🚀 Features Added

1. 🔁 Persistent Message History

• Integrated the shared history.History module (pkg/history) into the TUI editor.
• All sent messages are now stored in a persistent history file (e.g., ~/.config/cagent/history.json).
• Message history is automatically reloaded between sessions, ensuring continuity across app restarts.
• Deduplication logic prevents storing consecutive identical messages.

---

2. ⬆️⬇️ Keyboard Navigation

• Implemented Up/Down arrow navigation inside the editor:

  • ↑ – Loads the previous message.
  • ↓ – Moves forward through history or restores the current draft when reaching the latest point.

• Navigation behavior:

  • Works only for single-line inputs to avoid interrupting multi-line editing.
  • Automatically exits browsing mode when typing resumes.
  • Keeps the cursor at the end of the recalled message for immediate editing.

---

3. 🧠 Draft Preservation

• When users start navigating through history, their current unfinished input (draft) is temporarily saved.
• If they navigate forward to the end of history, their draft is restored — preventing accidental data loss.

---

4. ⚙️ Chat Page Integration

• The chatPage now initializes and shares a single History instance with the Editor.
• On each message send (SendMsg), the message content is appended to history before being processed by the runtime.
• Ensures both components operate with a single source of truth for command history.

---

5. 💬 UX Improvements & Reliability

• Smooth no-op behavior when history is empty or unavailable.
• Editor remains fully functional even if history initialization fails.
• Maintains all previous keyboard behavior (Enter → send message, Ctrl+C → quit).

---

🔒 Error Handling & Safety

• Gracefully handles missing or corrupted history files.
• Avoids panics and fatal dependencies.
• Operates in degraded mode (no history) if initialization fails.

---

✅ Result:
Users get a familiar and efficient workflow for recalling and reusing past commands — improving productivity and chat experience within the TUI.

[riturajFi]

@dgageot kindly review

[dgageot]

@riturajFi I'm not sure I understand the code. It seems to me that it could be simpler. Also, it seems to store the same messages twice in the history. I think it's better if we can avoid that.

[riturajFi]

Thanks @dgageot , doing changes right aw3

[riturajFi]

Hi @dgageot,
I’ve added comments throughout my solution to improve readability and clarity.
I’ve kept the code intentionally simple, but I’d appreciate your feedback on whether the structure makes sense architecturally.

A few notes:

1. The add-to-history logic currently resides in the chat page, though it could be moved into the editor for better encapsulation if you think that’s cleaner.
2. I verified that there’s no duplicate message saving issue — checked the history.json file to confirm:

   riturajtripathy@riturajtripathy-IdeaPad-Slim-3-15ABR8-1: cat /home/riturajtripathy/.cagent/history.json
    {"messages":["hi","ji"]}
   

Let me know your thoughts or if you’d prefer a different architectural direction.

[rumpl]

Just coming back to say: Thank you!

I spent the whole evening using this all the time, such a great little feature