feat: persistent command layer (vim-like navigation mode)

[adrien-barret]

What

Adds a persistent, vim-like command layer (Mode::FocusNav) — a normal-mode
counterpart to the terminal's insert mode. Enter it via a configurable focus_nav
keybind and the whole prefix keymap goes live on bare keys, staying open across
actions instead of exiting after one:

• Movement and actions use your existing prefix bindings without the prefix:
  h/j/k/l focus panes, c new tab, v / - split, p / n switch tabs,
  w workspace picker, x close, z zoom, and so on.
• The mode stays open after each action — chain as many as you like.
• Escape (or re-pressing the trigger) exits back to the terminal.

A CMD status bar is shown while the layer is active.

Text dialogs suspend and return

Actions that open a text input (rename workspace/tab/pane, new-tab / new-workspace
name prompts, confirm-close) suspend the command layer so you can type. On
commit or cancel you return to the command layer — not to the terminal — so an
accidental rename never drops you out of navigation.

Why

Today, movement in the live layout is one-shot: prefix+h/j/k/l moves focus once
and returns to the terminal, and goto / workspace_picker are pickers that close
on selection. There is no sticky, modal layer to drive herdr with bare keys. This
adds a familiar normal/insert split over panes, tabs, and workspaces, reusing the
existing keymap so there is nothing new to learn.

Design

• New Mode::FocusNav; handle_focus_nav_key dispatches the same prefix keymap
  (non_indexed_action_for_key / command_for_key / indexed_navigation_action
  with BindingDispatch::Prefix) but never auto-exits.
• New AppState.command_layer flag, set on entry and kept across dialogs. The
  shared return helpers (leave_navigate_mode, leave_command_mode, leave_modal,
  confirm_close_cancel) route back to Mode::FocusNav while the flag is set — this
  is what makes dialogs suspend-and-return.
• New bindable action EnterFocusNav, wired as focus_nav, unset by default —
  no change to existing keymaps. Existing Navigate / Navigator behavior is
  untouched.

Config

[keys]
focus_nav = "prefix+space"   # unset by default

Testing

• nix build .#herdr passes.
• herdr config check accepts focus_nav and still flags unknown keys.
• Manual: enter the layer, chain pane/tab/workspace actions, open a rename dialog
  and confirm both commit and Escape return to the command layer; Escape from the
  layer returns to the terminal.

[kangal-bot]

Hi @adrien-barret, thanks for your interest in contributing.

Herdr does not accept unsolicited implementation pull requests from contributors who are not listed in .github/APPROVED_CONTRIBUTORS.

The pull request author is not an approved contributor.

If you encountered a reproducible bug, report the observed behavior through the bug issue template. A report does not reserve the work or authorize a pull request; accepted fixes are normally implemented by Herdr’s maintainer-controlled agents.

Feature requests, behavior changes, and other proposals belong in GitHub Discussions. Do not open an issue merely to justify an implementation that was already written.

If a maintainer explicitly wants this implementation, they can reopen the pull request. Reopening by anyone else will be closed again automatically.

See https://github.com/herdrdev/herdr/blob/master/CONTRIBUTING.md for the contribution policy.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 53f17736-585a-4c02-baf4-8749032954b2

📥 Commits

Reviewing files that changed from the base of the PR and between 952729e and 3fcae32.

📒 Files selected for processing (9)

• src/app/input/mod.rs
• src/app/input/modal.rs
• src/app/input/navigate.rs
• src/app/mod.rs
• src/app/state.rs
• src/config/keybinds.rs
• src/config/model.rs
• src/ui.rs
• src/ui/menus.rs

---

📝 Walkthrough

Walkthrough

The application adds a configurable Mode::FocusNav. Users can enter it through a navigation action, move focus across panes, tabs, and workspaces, exit with configured keys, and view navigation hints in the mode bar.

Changes

Focus navigation

Layer / File(s)	Summary
Configure the focus-navigation action src/config/keybinds.rs, src/config/model.rs	Keybinding models, defaults, overlays, validation, deserialization, and profile generation now include focus_nav.
Enter focus-navigation mode src/app/input/navigate.rs, src/app/state.rs	EnterFocusNav resolves through the configured binding and switches TUI and test navigation into Mode::FocusNav.
Route and process focus-navigation keys src/app/input/mod.rs, src/app/mod.rs, src/app/input/modal.rs	FocusNav keys reach handle_focus_nav_key, which dismisses update notifications, exits on configured keys, and navigates panes, tabs, and workspaces.
Render the focus-navigation overlay src/ui.rs, src/ui/menus.rs	The mode bar renders a NAV overlay with pane, tab, workspace, and exit key hints.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant TerminalKey
  participant Keybinds
  participant NavigateAction
  participant App
  participant UI
  TerminalKey->>Keybinds: resolve focus_nav
  Keybinds->>NavigateAction: return EnterFocusNav
  NavigateAction->>App: switch to Mode::FocusNav
  TerminalKey->>App: send navigation key
  App->>App: handle_focus_nav_key
  App->>UI: render focus-navigation overlay

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Possibly related PRs

• herdrdev/herdr#2271: Both changes modify keyboard navigation and keybinding handling.
• herdrdev/herdr#2340: Both changes modify navigation-mode key handling.
• herdrdev/herdr#2558: Both changes extend NavigateAction and keybinding configuration.

Suggested labels: ai-review

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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⚠️ This pull request shows signs of AI-generated slop (description_diff_mismatch). It has been flagged by CodeRabbit slop detection and should be reviewed carefully.

[adrien-barret]

@coderabbitai review

[coderabbitai]

⚠️ Action not completed

Pull request is closed.

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