fix(archive): stop "Archive running task?" dialog firing on idle tasks

[adboio]

Problem

The "Archive running task?" confirmation was popping up on nearly every archive, even for tasks that weren't running.

The guard in SidebarMenu.tsx was:

task.taskRunStatus === "in_progress" || task.isGenerating

where taskRunStatus falls back to task.latest_run.status. That persisted status is only kept current by the backend for cloud runs (it flips to completed/failed/cancelled when the sandbox finishes or crashes).

Local runs never get a terminal status written back — nothing PATCHes the run when the local agent goes idle or the app closes — so latest_run.status stays "in_progress" forever. Once there's no live session, the guard read that stale status and treated the task as running.

Fix

Moved the predicate into core as a pure, tested helper (packages/core/src/sidebar/taskRunning.ts, mirroring runEnvironment.ts) and corrected the logic:

export function isTaskActivelyRunning(task: TaskData): boolean {
  if (task.isGenerating) return true;
  return task.taskRunEnvironment === "cloud" && task.taskRunStatus === "in_progress";
}

• Local tasks count as running only while a prompt is actually in flight (isGenerating); the stale persisted status is ignored.
• Cloud tasks keep the reliable, backend-tracked in_progress signal — behaviour unchanged.

This matches the existing session-based "running" logic in canvasGenerationStatus.ts and how TaskIcon already gates run-status semantics to cloud tasks.

Testing

• New parameterised test taskRunning.test.ts (12 cases), including the exact regression: stale local in_progress with no live prompt → not running.
• pnpm --filter @posthog/core test → 185 files / 1859 tests pass.
• typecheck (core + ui) and biome lint clean.

Note (out of scope)

The mobile guard (apps/mobile/.../archiveGuard.ts) uses raw !isTerminalStatus(latest_run.status), which has the same latent flaw for local tasks — only sound today because mobile is cloud-only. Left untouched here.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit b0d2ef0.}

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix(archive): stop the "Archive running ..." | Re-trigger Greptile}

[github-actions]

Well-targeted bug fix: extracts a pure predicate into @posthog/core (correct layer), fixes the stale in_progress status problem for local runs, and ships 12 parameterised test cases that explicitly cover the regression. Architecture rules are satisfied — @posthog/ui importing from @posthog/core is explicitly permitted, and the function has no host dependencies.

[github-actions]

Focused, well-tested bug fix: extracts a pure predicate to the correct layer and corrects the stale in_progress status problem for local runs. No showstoppers.