fix(FUX-039): add release changeset for runtime-fallback viewport hardening

[gsxdsm]

Summary

003948033 ("harden runtime-fallback agent-card viewport gating") landed on main without a changeset, but it affects published @runfusion/fusion. This PR adds the missing patch changeset so the fix shows up in release notes.

Context

Supersedes the now-closed #1963, whose code was fully redundant with main — all four FUX-039 findings plus every Greptile/CodeRabbit review comment already shipped via 003948033 and the preceding FUX-039 commits. The only remaining gap was this release-notes entry.

What the changeset documents

• summary (user-facing): Prevent redundant polling and a re-render loop in agent-card runtime-fallback badges.
• category: fix
• dev: AgentsView caches one stable ref callback per viewport key (avoids an infinite re-render loop when IntersectionObserver is unavailable) and evicts it on unmount; the test-only toast-dedupe reset is guarded to a no-op in production builds.

Status

• Diff: a single new file under .changeset/. No production code changes.
• Gate: ✅ green — Lint, Typecheck, Build, and Gate all pass on d8ce3f408.
• An earlier revision also trimmed fn-7692's over-length summary to unblock the gate, but main since fixed that itself in 5815cd170, so this branch was rebased to drop the now-redundant commit. The diff is now purely the FUX-039 changeset.

🤖 Generated with an autonomous coding agent

[greptile-apps]

No reviewable files after applying ignore patterns.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR adds a single changeset file documenting a patch release for @runfusion/fusion, describing fixes to agent-card runtime-fallback badge behavior including viewport-key ref-callback caching and a production-guarded toast-dedupe reset.

Changes

Changeset Documentation

Layer / File(s)	Summary
Add patch changeset .changeset/fux-039-runtime-fallback-review-polish.md	Documents a patch release fixing redundant polling and re-render loops in agent-card runtime-fallback badges, noting viewport-key ref-callback caching and a production-guarded test toast-dedupe reset.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Linked Issues check	❓ Inconclusive	This PR only adds a changeset, so the linked code-fix objectives aren't verifiable from the provided diff.	Include the implementation diff for the runtime-fallback fixes, or link the merged code changes, so the issue can be validated.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Out of Scope Changes check	✅ Passed	The only change is a release changeset for the documented runtime-fallback fix, with no unrelated code added.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: adding a release changeset for runtime-fallback viewport hardening.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fux-039-changeset

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