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+# TUI Column Navigation & Session Archiving — Design
+
+**Date:** 2026-06-11
+**Status:** Approved (ready for implementation plan)
+
+## Goal
+
+Two TUI-UX improvements to hqt's main view:
+
+1. **h/l column navigation** — vim-style horizontal movement between the Projects and Sessions columns, complementing the existing `j/k` within-list movement.
+2. **Session archiving** — a recoverable "remove from view" that tears down a finished session's tmux window but keeps its DB record, with a per-project toggle to view and restore archived sessions.
+
+## Background / Current State
+
+- Main view (`src/hqt/tui/app.py`) composes `ProjectList` (docked left) + `SessionList` (fills right) + `Footer`.
+- Within-list movement uses `VimListView` (`j`/`k` plus arrows). Cross-column movement today is `Tab` → `screen.focus_next()` (cycles ProjectList → SessionList → Footer).
+- `Session` and `Project` models already carry an `archived: bool` column (`src/hqt/db/models.py`). Every session read path already filters `archived=False` (`list_sessions`, `sync_window_labels`, `session_id_for_window`). **No DB migration is required** — the column exists at baseline schema v1.
+- `delete_session` (`src/hqt/sessions/service.py`) kills the tmux window (if alive), removes any worktree (optional), deletes the scheduled prompt, and deletes the DB row. Archiving will reuse the window-teardown portion of this path.
+
+## Feature A — h/l Column Navigation
+
+Add two app-level bindings in `app.py`:
+
+- `h` → `action_focus_projects`: focus the `#project-list` `VimListView`.
+- `l` → `action_focus_sessions`: focus the `#session-list` `VimListView`.
+
+These focus a specific widget by id (not `focus_next()`), so they are directional regardless of current focus. The existing `Tab` → `action_toggle_focus` binding **stays** as a cycle alias. No CSS/layout changes.
+
+**Behavior details:**
+- Selecting a project continues to drive which sessions are shown (unchanged).
+- Pressing `l` when the selected project has zero sessions still moves focus to the (empty) Sessions list — consistent with how `Tab` behaves today.
+
+## Feature B — Session Archiving
+
+### Semantics
+
+Archiving is a **recoverable delete**: it kills the session's tmux window/harness process (freeing resources) but **keeps the DB row** including `harness_session_id`, so the record can be referenced or restored later. It is the everyday "I'm done with this" action; hard `delete` remains for permanent removal.
+
+### Service layer (`src/hqt/sessions/service.py`)
+
+- Parameterize the read path: `list_sessions(project_id, archived=False, now=None)` — same query, with the archived flag configurable.
+- `archive_session(session_id)`: kill the tmux window if it exists (reuse the existing teardown used by `delete_session`), then set `archived=True` and commit. Does **not** remove the worktree or DB row.
+- `unarchive_session(session_id)`: set `archived=False` and commit. The window stays gone — the restored session is a dead, recoverable record.
+
+`sync_window_labels` and other live-session machinery continue to filter `archived=False`, so archived rows are never polled or labeled.
+
+### TUI actions & keybindings (`src/hqt/tui/app.py`)
+
+| Key | View      | Action                                                         |
+|-----|-----------|----------------------------------------------------------------|
+| `x` | active    | Archive selected session — gated behind the same confirm dialog as delete |
+| `A` | both      | Toggle the Sessions column between **active** and **archived**  |
+| `u` | archived  | Restore (unarchive) the selected session                        |
+| `d` | both      | Hard delete (unchanged; in archived view the window is already gone) |
+
+### View toggle
+
+- A `_show_archived: bool` flag on the app. `action_toggle_archived` flips it and refreshes the Sessions list for the currently-selected project.
+- When archived, the Sessions header reads **"Sessions (archived)"**; when active it reads **"Sessions"**.
+- The flag **persists across project switches** (predictable, single global mode). `_refresh_sessions` reads `archived=self._show_archived` when calling `list_sessions`.
+- Footer adapts via Textual's `check_action`: `x` is offered only in active view, `u` only in archived view. The footer never advertises an inapplicable action.
+
+### Status of archived sessions
+
+Archived sessions always render as `dead` (their window was killed). No pane capture or status parsing is needed for them; `_poll_sessions` continues to operate on the active list only.
+
+## Out of Scope
+
+- Archiving **projects** (the `Project.archived` column exists but no project-archiving UI is part of this work).
+- Worktree removal on archive (archive keeps the row and any worktree; hard delete still handles worktree teardown).
+- Bulk archive/restore.
+
+## Testing
+
+**Service tests (`tests/test_sessions.py`):**
+- `archive_session` kills the window, keeps the row, and the row is excluded from `list_sessions(archived=False)`.
+- `unarchive_session` makes the row reappear in the active list.
+- `list_sessions(project_id, archived=True)` returns only archived rows.
+
+**TUI tests (`tests/test_tui*.py`, following existing patterns):**
+- `x` triggers archive (with confirm), `A` toggles the view and header text, `u` restores.
+- `h`/`l` move focus to the projects/sessions lists respectively.
+- Footer/`check_action` adaptation: `x` hidden in archived view, `u` hidden in active view.