refactor: extract CommandHandler from GeneralKeyboardIME (Part 14) - #426

[prince-0408]

Description

This PR is Part 14 in modularizing GeneralKeyboardIME for #426.

It extracts command execution logic (handleKeycodeEnter), translation and plural lookup result handling (handlePluralOrTranslateState), verb conjugation query dispatching (handleConjugateState), standard editor action execution (handleDefaultEnter), and result output committing (applyCommandOutput) out of GeneralKeyboardIME.kt into a standalone helper class CommandHandler.

Detailed Changes Table

File / Component	Changes Applied	Detailed Impact
CommandHandler.kt	Created standalone helper encapsulating Enter key state dispatching (handleKeycodeEnter), command lookup result processing (handlePluralOrTranslateState, handleConjugateState), standard editor action execution (handleDefaultEnter), and output result committing (applyCommandOutput).	Extracts command execution logic, Enter key dispatching, and lookup state transitions out of GeneralKeyboardIME.kt into a dedicated helper class.
GeneralKeyboardIME.kt	Instantiated commandHandler and delegated command methods (handleKeycodeEnter, applyCommandOutput). Updated helper visibilities (getPluralRepresentation, getTranslation, refreshUI, applyCapitalizationToConjugations, currentVerbForConjugation, conjugateOutput, conjugateLabels) to internal.	Fulfills the core goal of #426 by decoupling command execution and lookup state transitions from GeneralKeyboardIME.kt while maintaining 100% backward compatibility for all callers.
CommandHandlerTest.kt	Added unit tests covering Enter key state transitions and output commit formatting.	Ensures unit test coverage for command handler logic.
CHANGELOG.md	Added entry under ### ♻️ Code Refactoring detailing the extraction of CommandHandler from GeneralKeyboardIME.	Satisfies ci_changelog_check workflow requirement for pull requests targeting main.

Key Benefits

• Decoupled Command Execution & Lookup State Machine: Removes command execution logic, translation/plural lookup handling, and verb conjugation query dispatching from GeneralKeyboardIME.kt.
• Improved Testability & Maintainability: Enter key state dispatching and command output formatting can now be tested and maintained independently of IME service lifecycles.

Related Issue

Refactors part of #426

[andrewtavis]

Thanks so much for this, @prince-0408! It would be really helpful to maybe get a checklist in the issue of all of the work that you would say is left in order to close this issue. This should include all the current PRs that are open and all the subtasks of the original task. In this way we can keep in mind what we have left to do and maybe set a goal to close the original issue, as I feel like its scope is getting a bit out of bounds.

Appreciate your continued efforts here!

[Roniscend]

@prince-0408 The 7 methods widened to internal here are adding up across the extraction PRs would it be worth defining an explicit interface that handlers receive instead, so the contract doesn't silently grow?

[prince-0408]

@prince-0408 The 7 methods widened to internal here are adding up across the extraction PRs would it be worth defining an explicit interface that handlers receive instead, so the contract doesn't silently grow?

Hey @Roniscend

Very true indeed. Passing the entire GeneralKeyboardIME object directly to handler methods results in internal visibility increasing silently among all extraction PRs.

Having an explicit interface contract (e.g. KeyboardIMEContext or KeyboardCommandContext) that handlers will take as opposed to the full IME class will make sure that only necessary callback APIs are available to handlers and nothing else.

As we are close to the end of the extraction process (Part 15 is the last component), we could either define this explicit interface contract among the handlers in Part 15 or in a subsequent PR immediately after Part 15. This will ensure that handlers strictly follow the interface without any delays in current modularization PRs.

Do let me know your thoughts on this approach.

[Roniscend]

@prince-0408 do the interface contract in a dedicated PR right after Part 15, not inside it, so it stays a clean, focused diff across all handlers.

[prince-0408]

@prince-0408 do the interface contract in a dedicated PR right after Part 15, not inside it, so it stays a clean, focused diff across all handlers.

This sounds good! In Part 15, I will ensure that the only thing done is extraction of KeyboardLayoutHandler and then create a separate PR afterwards to define the interface contract across all handlers.