ci: run every workflow on GitHub-hosted runners

[bk-agent-01]

Problem

The repository moved to the personal account iamtushar324, and the Blacksmith runner app isn't installed there. Every job on a blacksmith-* label has queued forever since the move. Stuck examples:

• CI on PRs since 2026-09-26 10:31 UTC;
• CI on expbkmain since 19:43;
• Release main since 14:20.

The repository is public, so GitHub's standard hosted runners are free. Per Tushar: do not use Blacksmith for this repository.

Fix

Every runs-on / matrix runner label in .github/workflows/ (12 files) now uses a GitHub-hosted image:

Blacksmith	GitHub-hosted
blacksmith-*-ubuntu-2404	ubuntu-24.04
blacksmith-*-macos-26	macos-26 (already used by bk-desktop-release.yml)
blacksmith-*-windows-2025	windows-2025

ci.yml's Check, Test and Test Server jobs get a 25-minute timeout, up from 10, because GitHub's runners have fewer cores. For reference, the full suite takes ~17 min on one GitHub runner in deploy-expbkt3.yml.

.github/actions/setup-apt-mirrors still works: it writes its own mirror list file (the name still says "blacksmith") before ci.yml's apt steps read it.

Evidence

This PR's own CI runs from the PR's workflow files, so its CI checks running and passing on GitHub runners is the proof. All workflow files parse as YAML.

Pushed as bk-agent-01, which has the workflow scope; tusharbhardwaj-bk's token doesn't. Upstream-owned workflow files change here, which costs one line per runs-on at the next upstream merge. .github/ is exempt from the fork-marker check.

Model/harness: Claude Opus 5.5 via Claude Code in T3 Code.

🤖 Generated with Claude Code

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ No successful main baseline artifact is available yet. This run establishes the initial measurement.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	—	13.8 KiB	—	15.1 KiB	✅
Codex	Thread snapshot wire	—	7.3 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Codex	Live turn WebSocket decoded	—	57.1 KiB	—	66.4 KiB	✅
Codex	Live turn messages	—	9	—	21	✅
Claude	Total thread wire	—	13.8 KiB	—	15.1 KiB	✅
Claude	Thread snapshot wire	—	7.3 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket wire	—	6.5 KiB	—	7.8 KiB	✅
Claude	Live turn WebSocket decoded	—	57.9 KiB	—	66.4 KiB	✅
Claude	Live turn messages	—	9	—	21	✅

Baseline: unavailable · PR result: ea03dc6 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.9 KiB
• Claude decoded thread snapshot: 115.6 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.