fix(agents): preserve volatile context source order

[KyleAMathews]

Summary

Remove a global .sort() by at timestamp in assembleContext() that was undoing the semantic reordering performed by reorderInterruptedRuns(). When SIGINT races ahead of buffered runtime writes, the interrupted assistant run now correctly appears before the interrupt marker in the model transcript.

Root Cause

assembleContext() collected volatile messages from all sources, then globally sorted them by their at (stream offset) value. Meanwhile, reorderInterruptedRuns() in the timeline layer intentionally reorders aborted runs before the SIGINT signal that raced ahead of them—giving the model a coherent transcript where the partial response precedes the interruption.

The global sort undid this reordering: the SIGINT (lower offset, because it's appended directly by the server) was placed before the aborted run output (higher offset, because it's buffered through the runtime producer). The model then saw an interruption marker before any assistant output, breaking transcript coherence.

Approach

Remove the volatileMessages.sort() call entirely. Volatile sources already return messages in their intended order—timelineMessages() projects through materializeTimeline() → reorderInterruptedRuns() to produce the correct model-facing sequence. The at field is preserved as metadata for budget truncation ranges and load tools, but no longer drives global ordering.

Key invariant: volatile messages appear in source-registration order (all messages from source A, then all from source B, etc.), with each source's internal order preserved exactly as returned.

Trade-off: budget truncation under pressure now drops messages from earlier-registered sources first (instead of oldest-by-timestamp first). This is the intended behavior—source ordering is more semantically meaningful than raw stream offsets.

Non-goals

• The CI hardening commit (2a95b8a17) is bundled here but independent—it adds CODEOWNERS for .github/, fork-PR guards on benchmarking/load-test workflows, and least-privilege permission tightening.

Verification

cd packages/agents-runtime
pnpm vitest run test/use-context-volatile-interleave.test.ts
pnpm vitest run test/timeline-context.test.ts

Files changed

File	Change
packages/agents-runtime/src/context-assembly.ts	Remove volatileMessages.sort() call
packages/agents-runtime/test/use-context-volatile-interleave.test.ts	Update existing test expectations, add at assertions, three-source ordering test, and end-to-end integration test wiring materializeTimeline through assembleContext
.github/CODEOWNERS	Require admin review for .github/ changes
.github/workflows/benchmarking.yml	Drop CONTRIBUTOR from trigger, add fork-PR guard
.github/workflows/load_test.yml	Add fork-PR guard
.github/workflows/ts_tests.yml	Downgrade packages: write → read
.github/workflows/changesets_release.yml	Remove cache: pnpm from setup-node
.changeset/fix-sigint-context-order.md	Changeset for @electric-ax/agents-runtime patch

[github-actions]

Electric Agents Desktop Builds

Build artifacts for commit 8c57408.

Platform	Status	Artifact
macOS Apple Silicon	Passed	DMG
macOS Intel	Passed	DMG
Windows x64	Passed	Installer
Linux x64	Passed	AppImage / deb

Workflow run

[github-actions]

Electric Agents Mobile Build

Android preview build for commit 8c57408.

Platform	Profile	Status	Build
Android	preview	Passed	EAS build

Workflow run

[kevin-dp]

This is changing the configuration of several CI workflows that seem unrelated to the goal of this PR.