Fixes #4473 - Re-engineerCommand system and Fix Menus

[tig]

Fixes

• Fixes Menu, Shortcut, etc... are broken - Introduce Command Bubbling #4473
• Fixes UICatalog only open the menu at first time by mouse #4624
• Fixes Make it easy for Tests to redirect Logging to test output #3972

Overview

Re-engineers the Terminal.Gui v2 command system for correctness, clarity, and composability. See docfx/docs/command.md for the complete deep dive.

What Changed

Core infrastructure (View.Command.cs):

• CommandRouting enum (Direct, BubblingUp, DispatchingDown, Bridged) replaces ad-hoc boolean flags
• Immutable CommandContext (readonly record struct) with WithCommand/WithRouting
• CommandOutcome enum with bool? conversion shims (migration deferred — see below)
• GetDispatchTarget / ConsumeDispatch virtuals for declarative composite-view dispatch
• CommandBridge for cross-boundary routing (weak refs, one-way)
• Route tracing via Trace.CommandEnabled (zero overhead in Release builds)
• _lastDispatchOccurred reset at handler entry to prevent stale-flag bugs

View-specific:

• Shortcut: Relay dispatch (ConsumeDispatch=false) with deferred completion via CommandView_Activated
• OptionSelector/FlagSelector: Consume dispatch (ConsumeDispatch=true), context-dependent targets
• MenuBar: Consume dispatch + OnActivating toggle logic for activation/deactivation
• MenuBarItem: CommandBridge.Connect for PopoverMenu, Bridged guard, IsInitialized guard
• Menu: OnActivating override dispatches to focused MenuItem
• Button: IAcceptTarget, Space/Enter → Command.Accept, does NOT raise Activating

Design

See plans/finalizing-command-system.md for:

• Architecture overview and design invariants
• Dispatch pattern summary (relay vs. consume)
• Phase B deviations from original plan (7 documented)
• All completed work with commit references

See plans/menubar-reengineer.md for MenuBar bug fixes and test migration.

Tests

Suite	Passed	Failed	Skipped
UnitTestsParallelizable	14,045	0	23
UnitTests	~1,001	0	~22

Old non-parallelizable MenuBarTests.cs deleted; ~30 modern parallelizable tests replace it.

Porting Guide: Migrating from v2_develop

This PR changes how Activating/Accepting events work. Code written against v2_develop will need updates.

The big win: No more e.Handled = true

Previously, every Accepting/Activating handler had to set e.Handled = true or the command system would misbehave (double-firing, unexpected bubbling, or the event being silently swallowed). This was a constant source of bugs. Now, Handled is only for cancellation — set it to true only when you want to prevent the action from proceeding.

// BEFORE (v2_develop) — Handled was mandatory boilerplate
button.Accepting += (s, e) =>
{
    DoSomething ();
    e.Handled = true; // REQUIRED or things break
};

// AFTER (this PR) — just subscribe, no Handled needed
button.Accepted += (_, _) =>
{
    DoSomething ();
};

Use Accepted/Activated instead of Accepting/Activating

Previously, Accepted didn't really work — the post-events were unreliable or missing. All real work had to go in the pre-events (Accepting/Activating). Now the two-phase model works correctly:

• Accepting/Activating (pre-events) — Use only for cancellation or validation. Set e.Handled = true to prevent the action.
• Accepted/Activated (post-events) — Use for reacting to completed actions. No Handled property — these are non-cancellable notifications.

// BEFORE (v2_develop) — work in pre-event, must set Handled
checkBox.Activating += (s, e) =>
{
    label.Text = $"Value: {((CheckBox)s!).Value}";
    e.Handled = true;
};

// AFTER (this PR) — work in post-event, state is already updated
checkBox.Activated += (_, _) =>
{
    label.Text = $"Value: {checkBox.Value}";
};

Quick migration checklist

Old pattern	New pattern
view.Accepting += (s, e) => { DoWork(); e.Handled = true; };	view.Accepted += (_, _) => { DoWork(); };
view.Activating += (s, e) => { DoWork(); e.Handled = true; };	view.Activated += (_, _) => { DoWork(); };
view.Accepting += (s, e) => { if (invalid) e.Handled = true; };	view.Accepting += (_, e) => { if (invalid) e.Handled = true; }; (unchanged — cancellation still uses pre-event)
override OnAccepting(args) { ...; return true; }	override OnAccepted(ctx) { ...; } (move work to post-event unless cancelling)
override OnActivating(args) { ...; return true; }	override OnActivated(ctx) { ...; } (move work to post-event unless cancelling)

Button no longer raises Activating

Button now maps all interactions (Space, Enter, mouse) to Command.Accept. It does not raise Activating/Activated. If you were subscribing to button.Activating, switch to button.Accepted.

EventArgs changes

• Accepting/Activating use CommandEventArgs (has Handled and Context)
• Accepted uses CommandEventArgs (has Context, no Handled)
• Activated uses EventArgs<ICommandContext?> (has Value, no Handled)
• ICommandContext provides Command, Source, Binding, and Routing for advanced scenarios

Remaining Work

• MenuBar bugs: Several MenuBar interaction bugs remain that are not yet captured by unit tests (e.g., arrow key navigation edge cases, mouse interaction scenarios, dynamic title/HotKey changes). See plans/menubar-reengineer.md → Remaining Work.
• Phase D: 267 AddCommand call sites need bool? → CommandOutcome migration. Purely mechanical; conversion shims exist.
• CommandManager extraction: View.Command.cs (1,043 lines, 6 responsibilities) is an SRP candidate. Deferred — route tracing provides sufficient debugging visibility for now.

[codecov]

Codecov Report

❌ Patch coverage is 80.83709% with 467 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.51%. Comparing base (7678411) to head (f79d564).
⚠️ Report is 2 commits behind head on v2_develop.

Files with missing lines	Patch %	Lines
Terminal.Gui/Views/Menu/PopoverMenu.cs	67.08%	29 Missing and 24 partials ⚠️
Terminal.Gui/Views/Menu/MenuBar.cs	81.81%	29 Missing and 17 partials ⚠️
Terminal.Gui/Views/LinearRange/LinearRange.cs	69.72%	23 Missing and 10 partials ⚠️
Terminal.Gui/ViewBase/View.Command.cs	88.66%	6 Missing and 22 partials ⚠️
Terminal.Gui/Views/Menu/MenuBarItem.cs	84.50%	15 Missing and 7 partials ⚠️
Terminal.Gui/Views/Selectors/SelectorBase.cs	62.71%	7 Missing and 15 partials ⚠️
Terminal.Gui/App/Tracing/LoggingBackend.cs	61.22%	14 Missing and 5 partials ⚠️
Terminal.Gui/Views/Shortcut.cs	91.51%	9 Missing and 10 partials ⚠️
Terminal.Gui/Views/ProgressBar.cs	25.00%	14 Missing and 1 partial ⚠️
Terminal.Gui/Input/CommandBridge.cs	73.58%	8 Missing and 6 partials ⚠️
... and 57 more

Additional details and impacted files

@@              Coverage Diff               @@
##           v2_develop    #4620      +/-   ##
==============================================
+ Coverage       77.34%   77.51%   +0.17%     
==============================================
  Files             450      457       +7     
  Lines           45200    45623     +423     
  Branches         6593     6745     +152     
==============================================
+ Hits            34959    35364     +405     
+ Misses           8352     8301      -51     
- Partials         1889     1958      +69     

Files with missing lines	Coverage Δ
Terminal.Gui/App/ApplicationImpl.cs	88.37% <ø> (ø)
Terminal.Gui/App/IApplication.cs	0.00% <ø> (ø)
Terminal.Gui/App/PopoverBaseImpl.cs	82.22% <100.00%> (+0.82%)	⬆️
Terminal.Gui/App/Runnable/SessionToken.cs	100.00% <100.00%> (ø)
Terminal.Gui/App/Tracing/ListBackend.cs	100.00% <100.00%> (ø)
Terminal.Gui/Configuration/Scope.cs	82.22% <ø> (ø)
Terminal.Gui/Configuration/SourcesManager.cs	96.40% <ø> (ø)
Terminal.Gui/Configuration/ThemeManager.cs	58.64% <ø> (ø)
Terminal.Gui/Drawing/Glyphs.cs	100.00% <100.00%> (ø)
Terminal.Gui/Input/CommandBindingsBase.cs	95.52% <100.00%> (ø)
... and 81 more

... and 7 files with indirect coverage changes

---

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[tig]

@tznind this is pretty ready. Would love your eyes on it please.

[Copilot]

Pull request overview

Copilot reviewed 154 out of 223 changed files in this pull request and generated 11 comments.

Files not reviewed (1)

• Terminal.Gui/Resources/Strings.Designer.cs: Language not supported

[tig]

I will merge this in the morning....