feat(updater): add background update indicator

[LRainner]

Summary

• check for updates in the background after startup and at most once every 24 hours
• persist newly discovered versions and show an orange indicator beside About until viewed
• reuse the existing update card and download flow without adding release notes or notifications
• grant the main window only the updater check permission

Validation

• Frontend tests: 47 passed
• Rust tests: 39 passed
• Settings E2E: 6 passed
• Production build
• Cargo check
• Clippy with warnings denied
• Rust format check
• git diff --check

Summary by CodeRabbit

• New Features

  • Added background update checks with retry and periodic scheduling.
  • Added a visible indicator for newly available updates in Settings.
  • Update status persists across app reloads and can be acknowledged from the About page.

• Bug Fixes

  • Improved update-state handling across app versions and repeated checks.

• Tests

  • Added coverage for persisted update indicators, state changes, throttling, and reload behavior.

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds persisted update-check state, background updater scheduling, and settings-page update indicators. The About navigation displays unseen updates, acknowledges them when opened, and receives state changes from background checks.

Changes

Update Indicator Flow

Layer / File(s)	Summary
Update state persistence and timing src/update-indicator.ts, src/update-indicator.test.ts	Adds validated storage state, update-seen tracking, version invalidation, throttling, retry timing, and tests for these behaviors.
Background update scheduling src-tauri/capabilities/update-check.json, src/main.ts	Enables updater checks for the main window and schedules delayed background checks that persist and emit update results.
Settings indicator integration src/settings.ts, src/settings.html, src/styles.css, e2e/settings.e2e.ts	Connects update events and persisted state to the About indicator, update card, styling, and reload coverage.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant MainProcess
  participant TauriUpdater
  participant SettingsPage
  participant AboutTab
  MainProcess->>TauriUpdater: check for available update
  TauriUpdater-->>MainProcess: return update result
  MainProcess-->>SettingsPage: emit UPDATE_STATE_EVENT
  SettingsPage->>SettingsPage: refresh update indicator
  SettingsPage-->>AboutTab: display update dot
  AboutTab->>SettingsPage: acknowledge known update

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Possibly related PRs

• LRainner/AgentCat#9: Both changes modify the settings About/update UI and updater integration.

🚥 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 clearly matches the main change: adding a background updater check and persisted update indicator.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/styles.css`:
- Line 119: Update the fill and stroke color value in the .settings-nav-icon svg
rule from currentColor to lowercase currentcolor to satisfy Stylelint's
value-keyword-case rule.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 9a7d1e6f-d45a-491d-a85e-b06f31fb656b

📥 Commits

Reviewing files that changed from the base of the PR and between c8eded8 and 18c9286.

⛔ Files ignored due to path filters (1)

• src-tauri/gen/schemas/capabilities.json is excluded by !**/gen/**

📒 Files selected for processing (8)

• e2e/settings.e2e.ts
• src-tauri/capabilities/update-check.json
• src/main.ts
• src/settings.html
• src/settings.ts
• src/styles.css
• src/update-indicator.test.ts
• src/update-indicator.ts

[coderabbitai]

📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Fix the configured Stylelint violation.

currentColor fails value-keyword-case; use currentcolor so Stylelint passes.

Proposed fix

-.settings-nav-icon svg { width: 17px; height: 17px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
+.settings-nav-icon svg { width: 17px; height: 17px; fill: none; stroke: currentcolor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change

	.settings-nav-icon svg { width: 17px; height: 17px; fill: none; stroke: currentColor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
	.settings-nav-icon svg { width: 17px; height: 17px; fill: none; stroke: currentcolor; stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }

🧰 Tools

🪛 Stylelint (17.14.1)

[error] 119-119: Expected "currentColor" to be "currentcolor" (value-keyword-case)

(value-keyword-case)

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@src/styles.css` at line 119, Update the fill and stroke color value in the
.settings-nav-icon svg rule from currentColor to lowercase currentcolor to
satisfy Stylelint's value-keyword-case rule.

Source: Linters/SAST tools