agentydragon(tasks): add task 31 display remaining context percentage in TUI

agentydragon/tasks/31-display-context-remaining-percentage.md

@@ -0,0 +1,28 @@
+---
+id: 31
+title: Display Remaining Context Percentage in codex-rs TUI
+status: Not started  # one of: Not started, Started, Needs manual review, Done, Cancelled
+summary: Show a live "x% context left" indicator in the TUI (Rust) to inform users of remaining model context buffer.
+goal: |
+  Enhance the codex-rs TUI by adding a status indicator that displays the percentage of model context buffer remaining (e.g. "75% context left").  Update this indicator dynamically as the conversation progresses.
+
+## Acceptance Criteria
+
+- Compute current token usage and total context limit from the active session.
+- Display "<N>% context left" in the status bar or header of the TUI, formatted compactly.
+- Update the percentage after each message turn in real time.
+- Ensure the indicator is visible but does not obstruct existing UI elements.
+- Add unit or integration tests mocking token count updates and verifying correct percentage formatting (rounding behavior, boundary conditions).
+
+## Implementation
+
+**How it was implemented**  
+- Extend the session state in `tui/src/app.rs` or relevant module to track token usage and context limit.
+- After each send/receive event, recalculate `remaining = (limit - used) * 100 / limit`.
+- Render the indicator via the status bar widget (`tui/src/status_indicator_widget.rs`), appending `"{remaining}% context left"`.
+- Add tests in `tui/tests/` that simulate message additions and assert the status rendering shows correct percentages at key usage points.
+
+## Notes
+
+- This feature helps users anticipate when they may need to truncate history or start a new session.
+- Future enhancement: allow toggling this indicator on/off via config.