Add observable call preview thumbnail in Video sdk

[rahul-lohra]

Goal

Add observable call preview thumbnail

Implementation

val thumbnail: StateFlow<String?> = MutableStateFlow(null)

🎨 UI Changes

None

Testing

None

Summary by CodeRabbit

• New Features
  • Added access to call thumbnail data through a new observable property. Thumbnails are automatically synchronized with server updates.

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-video-android-core	12.00 MB	12.00 MB	0.00 MB	🟢
stream-video-android-ui-xml	5.68 MB	5.68 MB	0.00 MB	🟢
stream-video-android-ui-compose	6.28 MB	6.28 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate failed

Failed conditions
D Maintainability Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

Catch issues before they fail your Quality Gate with our IDE extension SonarQube for IDE

[coderabbitai]

Walkthrough

A new getThumbnail() method returning StateFlow<String?> was added to the CallState class. The internal thumbnail state is populated from server response data during call updates, providing external consumers access to observable thumbnail information.

Changes

Cohort / File(s)	Summary
New Thumbnail Property stream-video-android-core/api/stream-video-android-core.api, stream-video-android-core/src/main/kotlin/io/getstream/video/android/core/CallState.kt	Added public getThumbnail() method and thumbnail StateFlow property to expose thumbnail state. Internal mutable state (_thumbnail) wired to populate from server response thumbnails.imageUrl in call update paths.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 A thumbnail springs to life today,
From API calls so far away,
StateFlow ripples, smooth and bright,
Hopping updates, pure delight!
Frame by frame, the bunny cheers,
A picture's worth, through the years!

🚥 Pre-merge checks | ✅ 1 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check	❓ Inconclusive	The description is minimal and vague. While it includes required sections (Goal, Implementation, UI Changes, Testing), they lack sufficient detail and context to understand the full scope of changes.	Expand the description with more details: explain the purpose and use case for the thumbnail, provide implementation context, clarify testing approach, and complete the contributor checklist items (CLA, assignment, changelog updates, test coverage).

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Add observable call preview thumbnail in Video sdk' clearly and specifically describes the main change: introducing an observable thumbnail property to the Video SDK.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feature/rahullohra/thumbnail

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[coderabbitai]

🧹 Nitpick comments (1)

stream-video-android-core/src/main/kotlin/io/getstream/video/android/core/CallState.kt (1)

669-671: Add KDoc and explicit type annotation to the new public thumbnail property.

Two nits on this new public API surface:

1. KDoc is missing. Per the coding guidelines, public APIs require /** ... */ documentation.
2. No explicit type annotation. Every other comparable public StateFlow property in this file carries an explicit : StateFlow<T> declaration (e.g., egress, recording, settings, …). Omitting it here is inconsistent.

✏️ Proposed fix

-    internal val _thumbnail = MutableStateFlow<String?>(null)
-    public val thumbnail = _thumbnail.asStateFlow()
+    internal val _thumbnail = MutableStateFlow<String?>(null)
+
+    /**
+     * A URL pointing to the call preview thumbnail image, or `null` if no thumbnail is available.
+     * Updated whenever new call state is received from the server.
+     */
+    public val thumbnail: StateFlow<String?> = _thumbnail.asStateFlow()

As per coding guidelines: "Use KDoc (/** ... */) for public APIs and complex subsystems."

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In
`@stream-video-android-core/src/main/kotlin/io/getstream/video/android/core/CallState.kt`
around lines 669 - 671, Add a KDoc block and an explicit public type annotation
to the new thumbnail property: document the property with /** ... */ describing
what the thumbnail represents and change the declaration to include the explicit
type StateFlow<String?> (matching the pattern used for other public StateFlow
properties). Ensure you still back it with the internal MutableStateFlow
_thumbnail and expose it via .asStateFlow() so the symbol names _thumbnail and
thumbnail remain unchanged.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In
`@stream-video-android-core/src/main/kotlin/io/getstream/video/android/core/CallState.kt`:
- Around line 669-671: Add a KDoc block and an explicit public type annotation
to the new thumbnail property: document the property with /** ... */ describing
what the thumbnail represents and change the declaration to include the explicit
type StateFlow<String?> (matching the pattern used for other public StateFlow
properties). Ensure you still back it with the internal MutableStateFlow
_thumbnail and expose it via .asStateFlow() so the symbol names _thumbnail and
thumbnail remain unchanged.

[aleksandar-apostolov]

Should be private like every other mutable backing field in this class (_settings, _transcribing, _team, etc.). internal exposes the MutableStateFlow to the entire module.