feat(mobile): add configurable default effort level

[Gilbert09]

Summary

• Ports desktop PR feat(settings): add configurable default effort level #2116 to the mobile app: adds a "Default effort level" preference that pre-fills the reasoning pill on the new-task composer.
• The setting accepts the five effort levels mobile's composer already supports (low/medium/high/xhigh/max) plus last_used, which remembers the user's most recent pick.
• New lastUsedReasoningEffort is updated whenever the user picks a reasoning level in either composer, so the last_used default has something to fall back on.
• All persisted in the existing preferencesStore. UI added under Settings > Input below "Initial task mode".

Test plan

• pnpm --filter @posthog/mobile test (preferences store unit tests + existing suite)
• Manually verify in the app: pick "Max" as default, open the new-task screen, confirm reasoning pill shows "Max"
• Switch the setting to "Last used", change the pill to "Low" while composing, reopen the new-task screen, confirm it remembers "Low"
• Setting persists across app restart

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
apps/mobile/src/features/preferences/stores/preferencesStore.test.ts:24-39
The setter tests only spot-check one or two values each, missing "low", "medium", "high", and "xhigh" for `setDefaultReasoningEffort` and all values except "xhigh" for `setLastUsedReasoningEffort`. The team's convention is to prefer parameterised tests — using `it.each` here would cover every valid effort level without the repetition.

```suggestion
  it.each(["low", "medium", "high", "xhigh", "max", "last_used"] as const)(
    "updates defaultReasoningEffort to %s via setter",
    (effort) => {
      usePreferencesStore.getState().setDefaultReasoningEffort(effort);
      expect(usePreferencesStore.getState().defaultReasoningEffort).toBe(
        effort,
      );
    },
  );

  it.each(["low", "medium", "high", "xhigh", "max"] as const)(
    "updates lastUsedReasoningEffort to %s via setter",
    (effort) => {
      usePreferencesStore.getState().setLastUsedReasoningEffort(effort);
      expect(usePreferencesStore.getState().lastUsedReasoningEffort).toBe(
        effort,
      );
    },
  );
```

_{Reviews (1): Last reviewed commit: "feat(mobile): add configurable default e..." | Re-trigger Greptile}

[greptile-apps]

The setter tests only spot-check one or two values each, missing "low", "medium", "high", and "xhigh" for setDefaultReasoningEffort and all values except "xhigh" for setLastUsedReasoningEffort. The team's convention is to prefer parameterised tests — using it.each here would cover every valid effort level without the repetition.

Suggested change

	it("updates defaultReasoningEffort via setter", () => {
	usePreferencesStore.getState().setDefaultReasoningEffort("max");
	expect(usePreferencesStore.getState().defaultReasoningEffort).toBe("max");
	usePreferencesStore.getState().setDefaultReasoningEffort("last_used");
	expect(usePreferencesStore.getState().defaultReasoningEffort).toBe(
	"last_used",
	);
	});
	it("updates lastUsedReasoningEffort via setter", () => {
	usePreferencesStore.getState().setLastUsedReasoningEffort("xhigh");
	expect(usePreferencesStore.getState().lastUsedReasoningEffort).toBe(
	"xhigh",
	);
	});
	it.each(["low", "medium", "high", "xhigh", "max", "last_used"] as const)(
	"updates defaultReasoningEffort to %s via setter",
	(effort) => {
	usePreferencesStore.getState().setDefaultReasoningEffort(effort);
	expect(usePreferencesStore.getState().defaultReasoningEffort).toBe(
	effort,
	);
	},
	);
	it.each(["low", "medium", "high", "xhigh", "max"] as const)(
	"updates lastUsedReasoningEffort to %s via setter",
	(effort) => {
	usePreferencesStore.getState().setLastUsedReasoningEffort(effort);
	expect(usePreferencesStore.getState().lastUsedReasoningEffort).toBe(
	effort,
	);
	},
	);

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/mobile/src/features/preferences/stores/preferencesStore.test.ts
Line: 24-39

Comment:
The setter tests only spot-check one or two values each, missing "low", "medium", "high", and "xhigh" for `setDefaultReasoningEffort` and all values except "xhigh" for `setLastUsedReasoningEffort`. The team's convention is to prefer parameterised tests — using `it.each` here would cover every valid effort level without the repetition.

```suggestion
  it.each(["low", "medium", "high", "xhigh", "max", "last_used"] as const)(
    "updates defaultReasoningEffort to %s via setter",
    (effort) => {
      usePreferencesStore.getState().setDefaultReasoningEffort(effort);
      expect(usePreferencesStore.getState().defaultReasoningEffort).toBe(
        effort,
      );
    },
  );

  it.each(["low", "medium", "high", "xhigh", "max"] as const)(
    "updates lastUsedReasoningEffort to %s via setter",
    (effort) => {
      usePreferencesStore.getState().setLastUsedReasoningEffort(effort);
      expect(usePreferencesStore.getState().lastUsedReasoningEffort).toBe(
        effort,
      );
    },
  );
```

How can I resolve this? If you propose a fix, please make it concise.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[github-actions]

Clean, additive mobile preference feature. The bot's outdated it.each suggestion is already addressed in the final test file. No data integrity, API contract, or security concerns.