fix: stabilize provider registry snapshots

[CodeZeno]

What Changed

Stabilizes provider registry snapshot handling by subscribing directly to provider snapshot PubSubs instead of deriving updates from Stream.fromPubSub, which could miss updates when no stream consumer was active yet.

Also avoids persisting transient “not checked yet” fallback snapshots over real cached provider state, and changes managed provider getSnapshot so it reuses the current snapshot when settings have not changed instead of forcing a fresh probe every time.

Tests were updated to cover the new subscription shape and to wait for async provider probe results more reliably.

Why

To improve slow start times mainly but also keeps provider status more stable across startup, reconnects, and settings refreshes.
Start times are now 2-3 seconds where previously were around 7-8 seconds.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

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Note

Medium Risk
Touches core provider aggregation logic (subscriptions, refresh/persist behavior) and adjusts async timing, so regressions could surface as missing/stale provider status or extra probes, though changes are localized and well-covered by updated tests.

Overview
Stabilizes provider snapshot aggregation and persistence. The registry now consumes provider updates via an explicit subscribeChanges subscription (added to ServerProviderShape/ProviderSnapshotSource) instead of relying on Stream.fromPubSub start timing, reducing dropped updates during instance rebuilds/startup.

Avoids overwriting cached state with transient fallbacks. Adds isUnprobedProviderSnapshot to detect “not checked yet” placeholder snapshots, skips persisting them, and only seeds boot-time fallback providers when no cached snapshot exists.

Reduces unnecessary reprobes and hardens tests. makeManagedServerProvider.getSnapshot now returns the current cached snapshot when settings haven’t changed, and tests were updated for the new subscription shape plus more reliable polling/real-timer waits and path resolution assertions.

^{Reviewed by Cursor Bugbot for commit dcb923c. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Fix provider registry snapshot stabilization by replacing stream subscriptions with PubSub

• Replaces Stream.runForEach(source.streamChanges, ...) with an explicit PubSub subscription via a new subscribeChanges API in ProviderRegistry.ts, reducing missed change events.
• Adds subscribeChanges to ServerProviderShape and ProviderSnapshotSource so providers expose a direct subscription alongside the existing stream.
• Introduces isUnprobedProviderSnapshot to prevent unprobed provider snapshots from being persisted to disk prematurely.
• Adds syncCurrentSourceSnapshot to drive initial state population using the current snapshot while respecting the unprobed persistence policy.
• Test fixes in ProviderRegistry.test.ts add subscribeChanges to fake instances and replace Effect.sleep with real-timer polling to reduce flakiness.

^{Macroscope summarized dcb923c.}

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 5576781. Configure here.}

[cursor]

Duplicate comment block accidentally left in code

Low Severity

There are two duplicate comment blocks at the end of the ProviderRegistryLive layer definition (lines 680-707) explaining the PubSub subscription pattern. One of these can be removed.

 

^{Reviewed by Cursor Bugbot for commit 5576781. Configure here.}

[CodeZeno]

Didn't touch that code

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR modifies provider persistence logic by introducing filtering for 'unprobed' providers and changes the subscription model from Stream to PubSub. While framed as test stabilization, the changes affect what gets persisted to disk at runtime, warranting human review.

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