NES: refactor InlineEditRequestLogContext state management

[ulugbekna]

Summary

Refactors InlineEditRequestLogContext state management to eliminate implicit icon state, unify logging paths, fix stale icon caching, and enforce lifecycle.

Fixes #308719, fixes #308720, fixes #308721, fixes #308722

Changes

1. Replace implicit _icon with explicit outcome state machine (#308719)

Replace the implicit _icon: Icon.t | undefined field with an explicit _outcome: LogContextOutcome discriminated union (8 states: pending, succeeded, noSuggestions, cached, cachedFromGhostText, skipped, cancelled, errored).

• _resolveIcon() is now a switch on _outcome — every state maps to exactly one icon
• _isCompleted stays orthogonal (lifecycle flag controlling spinner text + Icon.check fallback)
• _setOutcome() warns on invalid re-transitions
• setIsCachedResult() refactored to direct field copy — avoids triggering cascading outcome transitions
• No caller changes required — public method signatures unchanged

2. Unify live and static log entry paths (#308720, #308722)

Remove the static add() path from InlineEditLogger — all entries now use the live pattern with callbacks.

• Ghost text provider now uses addLive() + markCompleted() in finally block, ensuring lifecycle is always closed
• Remove redundant add() call in NES inlineCompletionProvider (was already a no-op)
• Eliminates the static snapshot path that was the source of frozen spinner bugs

3. Fix stale icon caching in ChatPromptItem (#308721)

Store the main entry reference in ChatPromptItem and always resolve the icon from it.

• setMainEntry() always sets iconPath (even to undefined), clearing any stale value
• withFilteredChildren() re-resolves from the entry ref via setMainEntry() instead of copying a potentially stale iconPath snapshot
• Makes stale icons structurally impossible

Testing

• All 7731 copilot unit tests pass (vitest)
• All hygiene checks pass
• TypeScript compilation clean (only pre-existing unrelated error in copilotcliSessionService.ts)

[Copilot]

Pull request overview

Refactors NES/ghost text request logging to make log-tree icons and lifecycle updates deterministic and avoid stale UI state, primarily by moving to explicit outcome state and live log entries.

Changes:

• Replaced implicit icon mutation in InlineEditRequestLogContext with an explicit outcome (LogContextOutcome) that drives icon resolution.
• Removed the static/snapshot InlineEditLogger.add() path so requests are logged via live callbacks (addLive) and updated via onDidChange.
• Fixed stale icon propagation in the request log tree by storing the main entry reference in ChatPromptItem and re-resolving icons.

Show a summary per file

File	Description
extensions/copilot/src/platform/inlineEdits/common/inlineEditLogContext.ts	Introduces explicit outcome state for icon resolution; refactors cached-result state copying.
extensions/copilot/src/extension/log/vscode-node/requestLogTree.ts	Ensures parent tree nodes re-resolve icons from the main entry to prevent stale icon caching.
extensions/copilot/src/extension/inlineEdits/vscode-node/parts/inlineEditLogger.ts	Removes static add/snapshot logging path; keeps only live entry logging.
extensions/copilot/src/extension/inlineEdits/vscode-node/inlineCompletionProvider.ts	Removes now-invalid static logger add call; relies on existing live logging.
extensions/copilot/src/extension/completions-core/vscode-node/extension/src/vscodeInlineCompletionItemProvider.ts	Switches ghost text logging to addLive() and completes the lifecycle with markCompleted().

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 1