sessions: share status progress indicator between header and list

[sandy081]

What

The session header (top of a session view) showed a static codicon for in-progress / needs-input sessions, while the sessions list showed the animated pixel spinner. This makes the header render the same animated progress indicator as the list, and extracts the shared logic so the two surfaces can't drift apart.

Changes

• New src/vs/sessions/browser/sessionStatusIcon.ts (sessions core layer):
  • getSessionStatusIcon(...) — status → codicon mapping (previously duplicated verbatim).
  • getSessionStatusIndicator(...) — resolves a discriminated SessionStatusIndicator (spinner vs icon) carrying the spinner variant, a cacheKey, and a ready-to-apply CSS color. Centralizes the spinner-vs-codicon decision, variant selection (grid for in-progress, ring for needs-input), and colors.
• sessionHeader.ts — now renders the animated pixel spinner for in-progress / needs-input (grid/ring variants), falling back to the static codicon when reduced motion is requested (IAccessibilityService). Re-renders react to reduced-motion changes via observableSignalFromEvent. Icon glyph/variant is cached so unrelated observable updates don't restart the animation.
• sessionsList.ts — refactored its icon block to use the shared getSessionStatusIndicator; removed the duplicated getStatusIcon method and local spinner-key constants.

Why this layer

browser/parts/ (core) must not import from contrib/ per src/vs/sessions/LAYERS.md — which is exactly why the logic was originally copied. Placing the helper in sessions/browser/ lets both the core SessionHeader and the contrib SessionsList reuse it without violating layering.

Notes for reviewers

• Each call site keeps its own DOM rendering (the list's crossfade swap vs. the header's simple reset) since those genuinely differ — only the shared decision logic is centralized.
• Behavior parity: identical statuses, variants, and theme colors as before.

Validation

• npm run compile-check-ts-native ✅
• npm run valid-layers-check ✅
• eslint on changed files ✅

Co-authored-by: Copilot 223556219+Copilot@users.noreply.github.com

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@benibenj

Matched files:

• src/vs/sessions/browser/parts/sessionHeader.ts

@lszomoru

Matched files:

• src/vs/sessions/services/sessions/browser/sessionsListModelService.ts

[Copilot]

Pull request overview

Centralizes session status → visual indicator logic so the session header and sessions list render the same progress UI (animated pixel spinner when motion is allowed; codicon fallback when reduced motion is requested), preventing drift between the two surfaces.

Changes:

• Introduces a shared getSessionStatusIndicator(...) helper (and underlying icon mapping) in src/vs/sessions/browser/ to unify spinner-vs-codicon decisions, variants, and colors.
• Refactors the sessions list row renderer to consume the shared indicator instead of duplicating icon/spinner logic.
• Updates the session header to render the same animated pixel spinner as the list, re-rendering on reduced-motion changes while caching the current glyph/variant to avoid restarting animations unnecessarily.

Show a summary per file

File	Description
src/vs/sessions/contrib/sessions/browser/views/sessionsList.ts	Replaces inline status icon/spinner logic with shared getSessionStatusIndicator output while preserving existing crossfade behavior.
src/vs/sessions/browser/sessionStatusIcon.ts	New shared status→indicator helper (codicon mapping + discriminated indicator result including spinner variant, cache key, and CSS color).
src/vs/sessions/browser/parts/sessionHeader.ts	Uses shared indicator to render animated pixel spinner in header (with reduced-motion fallback), and avoids restarting animation on unrelated observable updates.

Copilot's findings

• Files reviewed: 3/3 changed files
• Comments generated: 4