refactor: restructure lib.rs into theme + router modules (#89)

[GeneralD]

Restructures src/lib.rs by extracting two focused modules, so the plugin's
zellij-facing glue, its pure click routing, and its theme adapter no longer
share one file. Pure mechanical-equivalence refactor — no behavior change,
no public API change, no new permission. Done as three independently
green commits, never a big-bang (the issue's core ask).

Closes #89.

What moved, and why

Commit	Module	Content	Rationale
1	src/theme.rs (new)	rgb + palette_from_style	The lone boundary touching both zellij's color types and the dependency-free color module — isolated as an adapter (rule #8)
2	src/router.rs (new)	pane_at / clicked_new_tab_button / clicked_close_button (now free functions) + TabPaneGeom	The pure, zellij-type-free click decisions a left-click resolves against the recorded frame
3	src/router.rs	new ClickIntent enum + route_click	One pure function resolves a click to a single intent; update() becomes the sole host-effect dispatcher

After commit 3, every host effect (new_tab, close_tab_with_index,
focus_terminal_pane, switch_tab_to) lives in exactly one place — the
update() LeftClick match arm — dispatched off the pure route_click
decision. The now-redundant focus_or_switch_at / switch_to_tab_at methods
are deleted.

Click routing priority (unchanged)

route_click composes the affordances in the order the bar paints them:

+ button (#76)  >  close × cell (#86)  >  minimap pane (#74)  >  tab block (#8)  >  no-op

Verification

All three commits build (wasm32-wasip1) and pass cargo test --lib green;
final state 243 tests pass, clippy adds no new warnings over baseline.

Four independent adversarial reviews (behavior-equivalence, #54 host-count
contract, rule-#8 boundary, coverage parity) all came back clean:

Review verdicts

• Behavior-equivalence: EQUIVALENT — priority order, false return on every path, host-effect args, the close_layout.clear()-before-close ordering, and the SwitchTab(u32) type all identical pre/post; no divergent-input counterexample found.
• Permission prompt is unfocusable: set_selectable(false) runs before the grant resolves #54 host-count contract: PRESERVED — the native-test stub trio is byte-identical, load still emits exactly 2 host commands and each PermissionRequestResult exactly 1, and the permission set stays ReadApplicationState + ChangeApplicationState (no third permission → no feat(title): pane-title summarization module (icon table + width-aware truncation) #15 freeze).
• Rule mouse: click a tab block to switch tabs #8 boundary: CLEAN — router.rs references zero zellij types; theme.rs is the only new module touching zellij_tile::prelude and leaks nothing past its color::Palette return; visibility stays pub(crate) (public API unchanged); content is English.
• Coverage: NO REGRESSION — TOTAL 99.52% vs 99.53% baseline (−0.01%, within the 1% project gate); router.rs and theme.rs both 100% line-covered; all moved tests keep their assertions; the deleted focus_or_switch_at smoke test is replaced by a stronger update()-driven focus/no-op test; a new route_click test covers all five ClickIntent arms.

Coverage note

The single off-wasm-uncovered line stays the new_tab dispatch arm — new_tab
reads a return value from stdin and panics under the native test host, so it is
inherently wasm-only (this was already uncovered at baseline). Its routing
decision (route_click → ClickIntent::NewTab) is fully covered in
router.rs; only the host call itself can't run off-wasm.

Deferred

The RenderGeometry bundle (folding the per-render geometry args into one
struct, the design's Step 4) is intentionally out of scope here and left to
a follow-up PR, to keep this change a clean extraction with no signature churn.

Summary by CodeRabbit

• Refactor

  • Reorganized internal click-handling logic and theme palette conversion into dedicated modules for improved code maintainability.

• Tests

  • Updated and expanded unit test coverage for click routing and theme palette generation.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8af125d9-27e7-4cd5-b277-3e8201c7ba6c

📥 Commits

Reviewing files that changed from the base of the PR and between c289641 and 0f17f46.

📒 Files selected for processing (2)

• .claude/rules/zellij-plugin-development.md
• src/theme.rs

📝 Walkthrough

Walkthrough

Two new crate-internal modules are introduced: src/router.rs provides pure click routing (hit-test predicates, TabPaneGeom, ClickIntent, and route_click), and src/theme.rs provides palette_from_style. src/lib.rs is updated to declare these modules, migrate State::tab_panes to router::TabPaneGeom, rewrite click dispatch through router::route_click, and remove five replaced in-file helpers and their associated tests.

Changes

Router and Theme Extraction

Layer / File(s)	Summary
Theme palette adapter src/theme.rs	Adds a private rgb helper and palette_from_style that converts a zellij Style into a renderer color::Palette using multiplayer_user_colors for slots, frame_highlight for the ring seed, and exit_code_error for the alert color. Unit tests verify slot ordering and ring derivation.
Router contracts: TabPaneGeom, predicates, ClickIntent src/router.rs	Defines TabPaneGeom to store per-render minimap geometry, adds three hit-test predicates (pane_at, clicked_new_tab_button, clicked_close_button), and introduces the ClickIntent enum enumerating all routing outcomes.
route_click orchestration and router tests src/router.rs	Adds route_click which applies a fixed priority order (new-tab button → close cell → pane focus → tab switch → NoOp), plus an extensive off-wasm test suite covering all predicates and priority resolution edge cases.
lib.rs wiring: module declarations, State update, helper removal src/lib.rs	Declares pub(crate) mod router and updates pub(crate) mod theme; migrates State::tab_panes to router::TabPaneGeom; rewrites update() to dispatch via router::route_click and router::ClickIntent; updates render() geometry construction; removes five replaced in-file helpers and their associated tests.

Sequence Diagram(s)

sequenceDiagram
  participant Plugin as ZellijPlugin::update()
  participant Theme as theme::palette_from_style
  participant Router as router::route_click
  participant Host as Zellij Host

  Plugin->>Theme: palette_from_style(&mode_info.style)
  Theme-->>Plugin: color::Palette
  Plugin->>Router: route_click(button_layout, close_layout, tab_layout, tab_panes, row, col)
  Router-->>Plugin: ClickIntent
  alt ClickIntent::NewTab
    Plugin->>Host: new_tab()
  else ClickIntent::CloseTab(idx)
    Plugin->>Host: close_tab_with_index(idx)
    Plugin->>Plugin: clear close_layout
  else ClickIntent::FocusPane(id)
    Plugin->>Host: focus_pane(id)
  else ClickIntent::SwitchTab(n)
    Plugin->>Host: switch_tab_to(n)
  else ClickIntent::NoOp
    Plugin->>Plugin: no action taken
  end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• GeneralD/zellij-tabmap#79: Implements the minimap-pane click hit-testing via tab_panes geometry that this PR refactors into the new router module.
• GeneralD/zellij-tabmap#81: Adds the "+" new-tab button line::ButtonHit-based recording that this PR migrates into router::clicked_new_tab_button and router::route_click.
• GeneralD/zellij-tabmap#53: Adds the src/lib.rs unit tests for click-geometry and pane-routing behavior that this PR replaces with router-module-driven equivalents.

Poem

🐇 Hop hop, the router's born today,
No more click-helpers in lib's fray!
TabPaneGeom now in its own nest,
ClickIntent dispatches each request.
Pure logic, tested, clean as a carrot—
The warren grows tidy, every pixel! 🥕

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: refactoring lib.rs by extracting theme and router modules.
Linked Issues check	✅ Passed	The PR implements the incremental extraction approach from #89, isolating click-routing logic and theme-adapter boundaries while maintaining test coverage and preserving module APIs.
Out of Scope Changes check	✅ Passed	All changes align with #89's goal of refactoring lib.rs into layered modules; no unrelated modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch refactor/89-lib-architecture

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[codecov]

Codecov Report

❌ Patch coverage is 98.77049% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/lib.rs	90.62%	3 Missing ⚠️

📢 Thoughts on this report? Let us know!

[Copilot]

Pull request overview

This PR refactors the crate’s src/lib.rs by extracting two focused, unit-testable modules—theme (zellij theme → renderer palette adapter) and router (pure click intent routing)—so zellij-host effects are dispatched in one place while pure decisions remain dependency-free.

Changes:

• Added src/theme.rs to isolate theme-to-color::Palette conversion (and its tests) from lib.rs.
• Added src/router.rs to consolidate click hit-testing into a pure route_click function returning a single ClickIntent.
• Updated src/lib.rs to use theme::palette_from_style and to dispatch mouse left-click host effects via router::route_click.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/theme.rs	New adapter module converting Style → color::Palette plus migrated test coverage.
src/router.rs	New pure click-routing module (ClickIntent + route_click) with focused unit tests.
src/lib.rs	Wires in the new modules; centralizes left-click host-effect dispatch via the router.

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