feat(dev): agent mode — --json NDJSON events, /__kody/dev/status, --ready-file, attach by kentcdodds · Pull Request #61 · kody-bot/cli

kentcdodds · 2026-10-15T05:56:43Z

Stack: #63 → #58 → #61 → #59 → #60

Intent

Third of five stacked kody dev PRs (base: the live reload PR). Lets agents drive kody dev without scraping human output.

Door: two-way

Cleanup: none

Summary

kody dev --json prints one JSON object per line on stdout, each with type and ts:
- ready {url, port, basePath, pid, statusUrl, buildId}
- rebuild_start {files}
- rebuild_ok {ms, buildId, restarted}
- build_error {file, line, col, message, diagnostics}
- runtime_error {message, stack, request}
- log {source, level, message, request}
Status lines stay on stderr.
GET /__kody/dev/status returns { ok, state, buildId, url, port, basePath, target, package, pid, lastRebuild, lastError }.
--ready-file <path> writes { url, port, basePath, pid, statusUrl } once the first build settles and removes the file on exit.
kody dev fetch attaches to a running kody dev for the same package and --target. It finds the server through a registry file in the user cache dir, confirms it via the status endpoint, and waits for any in-progress rebuild. --no-attach forces a one-shot server. Attached fetches get no live-reload script.
The stat poll is re-baselined after each build, so it no longer causes a duplicate no-op rebuild.

Testing

npm run validate passes.
New test/dev-agent.test.ts covers: status through ready, runtime error, and build error states; --json event order with ts; the ready file and registry existing at ready and removed on shutdown; attached fetch seeing a fresh build, and not attaching across targets; and stale registrations being dropped.
Manual end-to-end run: the ready file, status JSON, NDJSON stream, and an attached kody dev fetch (132ms) all worked.

Note

Medium Risk
Touches dev-server request gating, file watching/rebuild scheduling, and cross-process registry files; mistakes could cause stale builds, duplicate rebuilds, or wrong attach targets, but scope is local dev tooling with tests.

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kentcdodds · 2026-10-15T06:00:10Z

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kentcdodds · 2026-10-15T06:11:53Z

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kentcdodds · 2026-10-15T06:20:20Z

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…eady-file, attach - kody dev --json prints ready / rebuild_start / rebuild_ok / build_error / runtime_error / log events as NDJSON on stdout. - GET /__kody/dev/status returns state, build id, and the last build or runtime error. - --ready-file writes { url, port, basePath, pid, statusUrl } once the first build settles and removes it on exit. - kody dev fetch attaches to a running kody dev for the same package and target (registry in the user cache dir, confirmed via status); --no-attach forces a one-shot server. - Live reload only injects into requests that accept text/html, so agent fetches see the app's bytes. - The watcher's stat poll re-baselines after each build (no echo rebuilds). - Dev server tests reuse the cached workerd instead of re-downloading it.

Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

Re-baseline after each build still suppresses echo rebuilds, but paths that changed since the previous baseline and were not the rebuild trigger fire onChange (mid-build edit). A track generation makes in-flight polls abandon so they cannot pair old fingerprints with the new map. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

Poll retains the map it started with so a concurrent track() swap cannot pair old fingerprints with the new baseline. Mid-build edits returned from track() are queued onto changedFiles/rebuildAgain directly instead of onChange, so a debounced chokidar delivery of the same paths cannot schedule a second rebuild. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

Prebuild (and similar) rewrite tracked inputs before esbuild runs. rebaseline() absorbs those fingerprints so track()'s mid-build comparison only reports edits that land during the bundle itself. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

kentcdodds · 2026-10-15T06:57:56Z

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Bugbot on #61: registry files are per root+target; remove only when the pid still matches (leave unreadable successor files alone); watcher debounce reports building and gates proxy fetches until the rebuild starts. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

kentcdodds · 2026-10-15T07:06:14Z

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kentcdodds · 2026-10-15T07:18:09Z

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kentcdodds · 2026-10-15T07:19:25Z

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Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

kentcdodds · 2026-10-15T07:22:43Z

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Bugbot: wrap post-listen ready-file/registration in shutdown-on-error so a bad --ready-file cannot leave listen handles hanging; poll also checks trackGeneration so an in-flight poll cannot echo rebuilds mid-track. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

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kentcdodds · 2026-10-15T07:26:55Z

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…lete Bugbot: no-op same-bundle rebuilds still update lastRebuild.at for agents polling status; findRunningDevServer re-reads before deleting a dead-pid entry so a successor registration is not wiped. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

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kentcdodds · 2026-10-15T07:33:30Z

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Detach the tracked fingerprint map at the start of track/rebaseline so an in-flight poll cannot compare post-build bytes to the pre-build baseline. Fold mid-build watcher events into the active loop, ignore echoes of the files already building, and skip buildOnce when every path still matches the baseline. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

…dits Fingerprint equality is not a reliable content check on coarse mtime filesystems, so skipping buildOnce when paths still matched the baseline could ignore real saves (e.g. v0→v1). Poll-map detach and mid-build chokidar folding remain the echo guards. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

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Ignoring onChange for paths in buildingFiles meant a second save (or format-on-save) during an in-progress rebuild was discarded, and track()'s ignoreChanges could not recover it — kody dev kept serving the earlier bundle. Fold every mid-build watcher event into rebuildAgain instead. Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

github-actions · 2026-10-15T08:02:01Z

🎉 This PR is included in version 1.25.0 🎉

The release is available on:

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kody-bot marked this pull request as ready for review October 15, 2026 06:00

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cursoragent and others added 5 commits October 15, 2026 06:51

fix(dev): only remove --ready-file when this process still owns it

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Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

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Intent

Summary

Testing

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