feat(ai-harness): build artifacts, worker mode, and remote harnessText by AlemTuzlak · Pull Request #1521 · TanStack/ai

AlemTuzlak · 2026-09-26T11:22:56Z

A harness can now run outside your server: as a worker process built with Bun, on another machine behind --serve, or as a single executable. buildHarness writes a bundle and a manifest, artifactText(dir) runs it as a model, and harnessText({ url, token }) talks to a remote harness. This is Phase 5 of the harness stack.

Stacked on #1520 (Phase 4) → #1519 → #1518 → #1515 → #1513 → #1509. Merge those first.

🎯 Changes

@tanstack/ai-harness/build: buildHarness({ entry, export, outDir, compile? }) bundles with Bun into harness.js and writes harness.manifest.json (name, agents, plugins, requirements, sha256 digest). artifactText(dir) checks the digest, starts one worker per outer thread, and is a text adapter with dispose(). readManifest(dir).
@tanstack/ai-harness/worker: runHarnessWorker(harness) serves session-tier frames as NDJSON on stdin and stdout.
harnessText({ url, token }): a remote harness (served by createHarnessHandler or runCli --serve) as a text adapter. It sends only the new message, because the remote session keeps the history.
Docs: docs/harness/deploy.md. Changeset: harness (minor).

✅ Checklist

I have followed the steps in the Contributing guide.
I have tested code changes locally with pnpm run test:pr, or these tests do not apply to this pull request.
I fully understand the code in this pull request, including any code generated with AI assistance.
Docs: I updated docs/ for this change, or this change is not user-facing.
Changeset: I added a changeset (pnpm changeset), or this PR does not change a published package.

🚀 Release Impact

This change affects published code, and I have generated a changeset.
This change is docs/CI/dev-only (no release).

Testing

Commands run (not the full pnpm test:pr, see below):

@tanstack/ai-harness: vitest run (72 passed, including a real Bun build and a worker process), tsc --noEmit, test:oxlint, build, test:build. @tanstack/ai-harness-cli: vitest run (8 passed).
testing/e2e: tsc --noEmit, playwright test tests/harness.spec.ts tests/harness-protocol.spec.ts (9 passed, including a remote harness over HTTP).
pnpm test:docs, kiira check docs/harness/deploy.md, pnpm test:sherif, pnpm test:knip.
Skipped the full pnpm test:pr run because it is slow on this machine. CI runs it.
The compile option is not run in tests (a Bun executable is about 100 MB).

Manual test

Install Bun. Run pnpm --filter @tanstack/ai-harness exec vitest run tests/build.test.ts. It writes a harness file, builds it, and chats with the worker twice.
Or follow docs/harness/deploy.md: buildHarness on a harness file, then chat({ adapter: await artifactText('./dist/studio'), ... }).

How this PR makes testing easy

packages/ai-harness/tests/build.test.ts: worker frames, remote harnessText, a real buildHarness run, artifactText keeping the conversation across calls, and a refused tampered bundle.
E2E: the remote scenario in testing/e2e/tests/harness.spec.ts calls the app's own protocol route over HTTP.

Risk / rollback

Low. New subpaths and a new harnessText overload. The build imports the user's entry in a child process (documented). Revert the PR to undo.

Public API change

Before

chat({ adapter: harnessText(studio, { host }), messages })

After

await buildHarness({ entry: './src/studio.ts', export: 'studio', outDir: './dist/studio' })
chat({ adapter: await artifactText('./dist/studio'), messages })
chat({ adapter: harnessText({ url: 'http://build-box:8787', token }), messages })

🤖 Generated with Claude Code

https://claude.ai/code/session_01APYv1qshKyjPPpkFyRZhfZ

Summary by CodeRabbit

New Features
- Harnesses can now connect to remote servers and stream text responses, with optional bearer-token authorization.
- Build harness artifacts or standalone executables, then run artifacts with per-thread conversations.
- Run harnesses as workers using a line-based protocol.
Documentation
- Added deployment guidance for running harnesses in servers, as worker artifacts, on remote machines, or as executables.

@tanstack/ai-harness/build: buildHarness bundles a harness with Bun into a worker artifact (harness.js) plus harness.manifest.json (name, agents, plugins, requirements, sha256 digest), and can compile a single executable. artifactText(dir) checks the digest, starts one worker process per thread, and uses it as a text adapter. @tanstack/ai-harness/worker: runHarnessWorker serves session-tier frames as NDJSON on stdin and stdout. harnessText({ url, token }) uses a harness served on another machine (for example with runCli --serve) as a text adapter.

coderabbitai · 2026-09-26T11:23:03Z

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📥 Commits

Reviewing files that changed from the base of the PR and between c2e6fb3 and b68dd47.

📒 Files selected for processing (14)

.changeset/harness-p5-build.md
docs/config.json
docs/harness/deploy.md
packages/ai-harness/package.json
packages/ai-harness/src/build.ts
packages/ai-harness/src/harness-text.ts
packages/ai-harness/src/index.ts
packages/ai-harness/src/worker.ts
packages/ai-harness/tests/build-stub.test.ts
packages/ai-harness/tests/build.test.ts
packages/ai-harness/tests/remote-worker.test.ts
packages/ai-harness/vite.config.ts
testing/e2e/src/routes/api.harness-test.ts
testing/e2e/tests/harness.spec.ts

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nx-cloud · 2026-09-26T11:24:39Z

View your CI Pipeline Execution ↗ for commit 458f665

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☁️ Nx Cloud last updated this comment at 2026-09-26 14:10:17 UTC

pkg-pr-new · 2026-09-26T11:27:33Z

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commit: b68dd47

…only where Bun exists

…feat/harness-p5-build

ci: apply automated fixes

5d27a1d

github-actions Bot assigned jherr Sep 26, 2026

github-actions Bot requested a review from jherr September 26, 2026 11:28

github-actions Bot added the waiting-on: author Waiting for the author to respond or update label Sep 26, 2026

AlemTuzlak mentioned this pull request Sep 26, 2026

feat(ai-dashboard): self-hosted dashboard, --dashboard, and a runnable example #1522

Open

7 tasks

AlemTuzlak added 3 commits September 26, 2026 13:58

Merge branch 'feat/harness-p4-subagents' into feat/harness-p5-build

bcf1b74

test(ai-harness): cover buildHarness without Bun, run the real build …

924aa4f

…only where Bun exists

Merge remote-tracking branch 'origin/feat/harness-p4-subagents' into …

461532b

…feat/harness-p5-build

This was referenced Sep 26, 2026

feat(ai-mcp, ai-harness): MCP connectors with browser sign-in, run-time tools, and media in the example #1523

Open

feat(ai-code-mode, ai-harness): code mode for harnesses with pluggable isolates #1524

Open

AlemTuzlak added 2 commits September 26, 2026 15:38

Merge remote-tracking branch 'origin/feat/harness-p4-subagents' into …

458f665

…feat/harness-p5-build

test(ai-harness): cover remote harnessText and worker edge frames

b68dd47

github-actions Bot added waiting-on: maintainer The ball is in the maintainers’ court and removed waiting-on: author Waiting for the author to respond or update labels Sep 26, 2026

AlemTuzlak added this pull request to stack #1536 September 28, 2026 08:53

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feat(ai-harness): build artifacts, worker mode, and remote harnessText - #1521

feat(ai-harness): build artifacts, worker mode, and remote harnessText#1521
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