fix(plugin-history-sync): add getServerSnapshot to useSyncExternalStore for SSR compatibility

[orionmiz]

Fixes #635

Fixes SSR error "Missing getServerSnapshot, which is required for server-rendered content" by adding the third parameter to useSyncExternalStore in plugin-history-sync.

The getServerSnapshot parameter is required for SSR environments to provide an initial snapshot value during server rendering.

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🦋 Changeset detected

Latest commit: ac50fb1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@stackflow/plugin-history-sync	Patch

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[coderabbitai]

📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Resolved server-side rendering (SSR) compatibility issue in the history sync plugin that was preventing proper rendering of server-rendered content in SSR environments.

Summary by CodeRabbit

• Refactor
  • Optimized internal synchronization mechanism for activity tracking to improve consistency and reliability.

Walkthrough

A third argument, getActivityActivationCounts, was added to the useSyncExternalStore call in the history sync plugin to provide the server snapshot parameter for SSR.

Changes

Cohort / File(s)	Change Summary
Hook parameter addition extensions/plugin-history-sync/src/historySyncPlugin.tsx	Passed getActivityActivationCounts as the third (server snapshot) argument to useSyncExternalStore

Sequence Diagram(s)

(No diagram provided — change is a single-argument addition to a hook call; no control-flow changes.)

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Pre-merge checks and finishing touches

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The pull request title "fix(plugin-history-sync): add getServerSnapshot to useSyncExternalStore for SSR compatibility" clearly and concisely describes the primary change in the changeset. It identifies the package being modified, the specific code change (adding getServerSnapshot parameter), and the motivation (SSR compatibility). The title is specific enough that a developer reviewing the repository history would immediately understand this patch addresses an SSR-related issue without needing to read the full description.
Linked Issues Check	✅ Passed	The code changes fully address the objective from linked issue #635. The PR adds the getServerSnapshot parameter as the third argument to useSyncExternalStore in historySyncPlugin.tsx, which directly resolves the reported error "Missing getServerSnapshot, which is required for server-rendered content." The changeset documentation confirms the patch adds SSR compatibility by introducing the required getServerSnapshot parameter, matching the issue's requirement to provide this implementation in SSR environments.
Out of Scope Changes Check	✅ Passed	All changes in this pull request are directly in scope with the linked issue #635. The modification to historySyncPlugin.tsx adds only the required getServerSnapshot parameter to useSyncExternalStore, and the new changeset file documents this specific patch release. No unrelated changes, refactoring, or other out-of-scope modifications appear to have been introduced alongside the core fix.
Description Check	✅ Passed	The pull request description is directly related to the changeset and provides meaningful context about the fix. It explains the specific SSR error being resolved, identifies the root cause (missing getServerSnapshot parameter), and clarifies why the parameter is required in SSR environments. The description references the linked issue (#635) and provides sufficient detail to understand the problem and solution without being verbose.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch claude/fix-issue-635-011CUPQPYvD8cK437EReGmS3

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📥 Commits

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📒 Files selected for processing (1)

• .changeset/fix-ssr-getServerSnapshot.md (1 hunks)

🧰 Additional context used

📓 Path-based instructions (1)

.changeset/*.md

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Include a Changeset entry for any user-facing package change

Files:

• .changeset/fix-ssr-getServerSnapshot.md

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🔇 Additional comments (1)

.changeset/fix-ssr-getServerSnapshot.md (1)

1-5: Changeset entry correctly documents the SSR compatibility fix.

The changeset follows the correct format with proper YAML front matter, appropriate patch bump level for this bug fix, and a clear description of the SSR error being resolved. The entry correctly documents a user-facing package change per coding guidelines.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
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