Fix #142: Prevent Design Switcher from briefly showing 'Offline'

[anshu10sep]

Summary

Fixes the Design Switcher briefly flashing "Offline" status when switching documents.

Problem

When enableLiveUpdates() is called, it sets up a coroutine to collect the Figma token from a DataStore-backed flow. The flow's initial emission is null (before the stored value is read from disk), which momentarily sets isDocumentLive to false. The Design Switcher reads this value and briefly shows the "Offline" variant.

Timeline

1. enableLiveUpdates() called
2. collectLatest starts → first emission is null
3. isDocumentLive = false  ← Brief 'Offline' flash
4. DataStore reads stored token → emits actual value
5. isDocumentLive = true   ← Back to 'Live'

Fix

Set isDocumentLive = true optimistically at the start of enableLiveUpdates():

// Set live status optimistically
isDocumentLive.value = true

// The coroutine will correct to false if no token is found
activity.lifecycleScope.launch { ... }

Behavior

Scenario	Before	After
Has token	Offline → Live (flash)	Live (stable)
No token	Offline → Live → Offline (flash)	Live → Offline

Changes

• designcompose/src/main/java/com/android/designcompose/DocServer.kt: Set isDocumentLive.value = true before launching the token collection coroutine

Validation

• ./gradlew designcompose:compileDebugKotlin: Passes ✅

Fixes #142

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 44.03%. Comparing base (af5409b) to head (9a4a39c).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2421      +/-   ##
============================================
- Coverage     44.05%   44.03%   -0.03%     
  Complexity       19       19              
============================================
  Files            39       39              
  Lines          4444     4444              
  Branches         51       51              
============================================
- Hits           1958     1957       -1     
- Misses         2472     2473       +1     
  Partials         14       14              

Flag	Coverage Δ
kotlin	72.17% <ø> (ø)
rust	41.66% <ø> (-0.03%)	⬇️

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[github-actions]

Snapshot diff report vs base branch: main
Last updated: Thu Apr 9 19:56:29 PDT 2026, Sha: 9a4a39c
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