[MarioCadenas]

What

Adds the new Databricks Apps model_service resource (a Unity Catalog securable of type MODEL_SERVICE, from databricks-eng/universe#2571640) and makes it the agents plugin's default-model resource.

Changes

• Resource type: model_service in resourceTypeSchema, permission EXECUTE. In databricks.yml it binds as uc_securable with securable_type: MODEL_SERVICE, mapping name to securable_full_name. Generated types, JSON schemas, plugin create defaults and docs updated.
• Agents plugin: the optional default-LLM resource is now model_service (agents-model-service, env DATABRICKS_MODEL_SERVICE_NAME, value catalog.schema.name). The agents plugin and standalone runAgent read that env first and still fall back to DATABRICKS_SERVING_ENDPOINT_NAME, so existing apps keep working.
• Routing: adapterFromModelString sends any dotted name to the AI Gateway (fromAiGateway), not only system.*. Model services are catalog.schema.name, and serving endpoint names cannot contain dots, so no existing endpoint changes route. To force a dotted name onto a serving endpoint, pass a pre-built adapter.
• appkit plugin add picker: opens on the system.ai model services, with "Browse other catalogs..." for a catalog, schema, model service drill-down. Uses databricks ai-gateway list-model-services, so it needs a CLI that has that command; otherwise it falls back to manual entry. --set / --from-plan accept any catalog.schema.name.
• appkit doctor: existence check for model_service (GET /api/2.1/unity-catalog/model-services/{name}).

Not changed

• The serving plugin stays on serving_endpoint. It is deprecated, and it calls /serving-endpoints/{name}/invocations, which a model service is not.
• No SCOPE_BY_TYPE entry for model_service, so the agents resource no longer carries a user API scope. Agents that run on behalf of the user may need ai-gateway; not added until confirmed.

Why the picker is a drill-down

A flat walk over every catalog and schema did not finish in 10 minutes on dogfood (1158 catalogs), and finding system by paging is slow, so the picker opens on system.ai and leaves the rest one pick away.

Testing

• Unit tests: schema and binding, picker steps (open on system.ai, browse, --set), doctor check, routing, agents env default.
• pnpm check, pnpm -r typecheck, pnpm test, docs build: green.
• Live on dogfood: doctor passes for system.ai.gpt-5-mini and reports NOT_FOUND for a made-up name; the system.ai listing returns 70 services; runAgent with DATABRICKS_MODEL_SERVICE_NAME=system.ai.gpt-5-mini answered through the AI Gateway.

Task: KIT-34 (app-kit/34)

This pull request and its description were written by Isaac.

[github-actions]

📦 Bundle size report

Compared against bundle-size-baseline.json (main).

@databricks/appkit

npm tarball (packed): 1.2 MB (+246 B) — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	1.3 MB (+520 B)	462 KB (+112 B)
Type declarations	468 KB (+3.3 KB)	169 KB (+69 B)
Source maps	2.5 MB (+995 B)	863 KB (+80 B)
Other	11 KB	3.7 KB
Total	4.3 MB (+4.8 KB)	1.5 MB (+261 B)

Per-entry composition (own code — deps external (as shipped))

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
.	107 KB (+74 B)	2.5 KB	110 KB (+74 B)	external	347 KB (+234 B)
./beta	103 KB (+87 B)	484 B	104 KB (+87 B)	external	311 KB (+341 B)
./testing	46 KB (+35 B)	33 KB	79 KB (+35 B)	external	229 KB (+232 B)
./tsdown	520 B	0 B	520 B	external	813 B
./type-generator	26 KB	0 B	26 KB	external	74 KB

Chunks:

Entry	Chunk	Load	Size (gz)
.	index.js	initial	103 KB
.	utils.js	initial	4.6 KB
.	remote-tunnel-manager.js	lazy	2.5 KB
./beta	beta.js	initial	83 KB
./beta	modular.js	initial	6.0 KB
./beta	stream-manager.js	initial	5.9 KB
./beta	service-context.js	initial	4.3 KB
./beta	databricks.js	initial	3.3 KB
./beta	client.js	initial	646 B
./beta	index.js	initial	20 B
./beta	supervisor-api.js	lazy	192 B
./beta	databricks.js	lazy	177 B
./beta	index.js	lazy	115 B
./testing	manifest.js	initial	33 KB
./testing	index.js	initial	10 KB
./testing	wide-event-emitter.js	initial	2.9 KB
./testing	index.js	lazy	29 KB
./testing	remote-tunnel-manager.js	lazy	2.5 KB
./testing	utils.js	lazy	1.8 KB
./tsdown	index.js	initial	520 B
./type-generator	index.js	initial	26 KB

@databricks/appkit-ui

npm tarball (packed): 397 KB — gzipped download (dist + bin; excludes release-only docs/NOTICE).

dist	raw	gzip
JS (runtime)	429 KB	147 KB
Type declarations	267 KB	98 KB
Source maps	848 KB	285 KB
CSS	16 KB	3.2 KB
Total	1.5 MB	533 KB

Per-entry composition (consumer bundle — deps bundled, peerDeps external)

Entry	Initial (gz)	Lazy (gz)	Total (gz)	node_modules (min)	Own code (min)
./js	5.3 KB	49 KB	55 KB	208 KB	14 KB
./js/beta	2.1 KB	0 B	2.1 KB	0 B	5.0 KB
./react	434 KB	49 KB	483 KB	1.3 MB	177 KB
./react/beta	4.9 KB	0 B	4.9 KB	0 B	12 KB

Chunks:

Entry	Chunk	Load	Size (gz)
./js	index.js	initial	5.2 KB
./js	chunk	initial	120 B
./js	apache-arrow	lazy	49 KB
./js/beta	beta.js	initial	2.1 KB
./react	index.js	initial	432 KB
./react	tslib	initial	2.1 KB
./react	apache-arrow	lazy	49 KB
./react/beta	beta.js	initial	4.9 KB

[github-actions]

🤖 AppKit PR bot

🔬 Run evals

Start an eval for this PR from the evals-monitor app: Go to Evals Monitor →

📦 Try this PR's app template

Scaffolds a new app from this PR's SDK build. Run it in any folder (requires the GitHub CLI — gh auth login — and the Databricks CLI):

gh run download 42808264577 -R databricks/appkit -n appkit-template-0.91.2-pr.3a37fb1-work-34-add-model-service-resource-rep-705 -D appkit-pr-705 \
  && unzip -o "appkit-pr-705/appkit-template-0.91.2-pr.3a37fb1-work-34-add-model-service-resource-rep-705.zip" -d "appkit-pr-705" \
  && databricks apps init --template "appkit-pr-705"

The template pins @databricks/appkit and @databricks/appkit-ui to tarballs built from this branch, so the scaffolded app runs against this PR's code.

[MarioCadenas]

Review 6 · Fail · 1 critical, 1 minor

Does the change do what the task asked? No. Gate: major and worse must be fixed.

The model_service resource type, its uc_securable MODEL_SERVICE/EXECUTE binding, the picker, the doctor check and the agents plugin switch are built, and the 262 related tests pass. The serving plugin is still on serving_endpoint, but the task says plainly to replace it in both plugins. The closing note cites a human decision to keep it, but there is no human message in the task log that confirms this.

Required

• critical: The serving plugin still declares serving_endpoint, not model_service, but the task says to replace it in both the serving and agents plugins. (packages/appkit/src/plugins/serving/manifest.json:11)
  Proof: The manifest has "type": "serving_endpoint" at line 11; the diff since 05c51e2 has no file under plugins/serving; said-by.jsonl has no human message saying serving stays as is (only the agent's closing-note says so). If that human decision is real, downgrade this.

Not required (below the gate)

• minor: Model services are listed by drilling down through the CLI rather than through a paginated ListModelServices in the workspace client, which is what item 2 asked for. (packages/shared/src/cli/commands/registry/workspace-picker.ts)
  Proof: The diff stat shows no file under packages/shared/src/workspace-client.

[MarioCadenas]

Review 7 · Pass · 1 minor, 1 trivial

Does the change do what the task asked? Yes. Gate: major and worse must be fixed.

model_service is added to the schema, DABs binding (uc_securable, MODEL_SERVICE, EXECUTE), doctor, the CLI picker (catalog > schema > ai-gateway list-model-services, prefix stripped) and the agents manifest and runtime env fallback, with tests that pass. The serving plugin staying on serving_endpoint and the CLI-based lister are human-settled decisions, so I don't count them as gaps.

Not required (below the gate)

• minor: Default-model routing widened from the system.* prefix to any dotted string, so any dotted value in DATABRICKS_SERVING_ENDPOINT_NAME or model now goes to AI Gateway instead of Model Serving. (packages/appkit/src/agents/databricks.ts adapterFromModelString)
  Proof: Diff: model.startsWith("system.") became model.includes("."); serving endpoint names cannot contain dots, so the impact is limited to invalid inputs.
• trivial: run-agent's no-model fallback still surfaces the DATABRICKS_SERVING_ENDPOINT_NAME error text, while the agents plugin now names DATABRICKS_MODEL_SERVICE_NAME. (packages/appkit/src/core/agent/run-agent.ts resolveAdapter)
  Proof: Read the diff: the comment and fromModelServing error path are unchanged.

[MarioCadenas]

Review 8 · Pass · 1 minor, 1 trivial

Does the change do what the task asked? Yes. Gate: major and worse must be fixed.

The model_service resource type, its uc_securable MODEL_SERVICE/EXECUTE binding, the paginated picker lister with prefix stripping, and the agents plugin and runAgent wiring are all in place and tested. The serving plugin stays on serving_endpoint, which the human settled. The one real gap: the agents resource no longer carries a user_api_scope, because model_service has no SCOPE_BY_TYPE entry.

Not required (below the gate)

• minor: model_service has no SCOPE_BY_TYPE entry, so the template's agents resource lost its "scope": "model-serving" and OBO agents get no user_api_scope for the default model. (packages/shared/src/schemas/manifest.ts:57 and template/appkit.plugins.json (agents optional resource))
  Proof: git diff 34b41cc...HEAD -- template/appkit.plugins.json shows the removed "scope": "model-serving" line; SCOPE_BY_TYPE has no model_service key. The agent flagged it as unconfirmed.
• trivial: Routing changed from startsWith("system.") to includes("."), so any dotted model string now goes to AI Gateway. Safe because serving-endpoint names cannot contain dots, but it is a behavior change. (packages/appkit/src/agents/databricks.ts:1015)
  Proof: Read in the diff.

[MarioCadenas]

Review 9 · Fail · 1 critical, 1 minor

Does the change do what the task asked? No. Gate: major and worse must be fixed.

The schema, DABs binding, CLI picker drill-down and agents plugin wiring for model_service are in place and their tests pass. But the serving plugin still declares serving_endpoint, which the task plainly asked to replace, and the lister was built as a CLI drill-down instead of the requested workspace-client SDK lister.

Required

• critical: The serving plugin manifest still declares a serving_endpoint resource (CAN_QUERY); the task said to replace it with model_service in the serving and agents plugins. (packages/appkit/src/plugins/serving/manifest.json:11, template/appkit.plugins.json:486)
  Proof: git diff 34b41cc...HEAD -- packages/appkit/src/plugins/serving is empty; rg shows "type": "serving_endpoint" at serving/manifest.json:11 and template/appkit.plugins.json:486

Not required (below the gate)

• minor: No workspace-client ListModelServices or SDK_LISTERS entry was added; model services are listed through a CLI PARENT_CONTEXT_CHAINS drill-down (databricks ai-gateway list-model-services), so the picker depends on the CLI having that command. (packages/shared/src/cli/commands/registry/workspace-picker.ts:363; packages/shared/src/workspace-client (unchanged))
  Proof: git diff 34b41cc...HEAD -- packages/shared/src/workspace-client is empty

[MarioCadenas]

Review 10 · Fail · 1 major, 3 minor

Does the change do what the task asked? No. Gate: major and worse must be fixed.

The model_service resource, its uc_securable/MODEL_SERVICE/EXECUTE binding, the picker lister, the doctor check and the agents plugin wiring are all built, and the targeted tests and typecheck pass. The serving plugin still uses serving_endpoint. The task said to replace it there too; the PR explains why it did not (the serving plugin calls /serving-endpoints/{name}/invocations), but a human has to accept that change of scope. The 3 red CI checks fail on template npm installs blocked by jfrog's 7-day age rule, and the branch does not cause them.

Required

• major: The serving plugin manifest still declares serving_endpoint; the task said to replace it with model_service in both the serving and agents plugins. (packages/appkit/src/plugins/serving/manifest.json:11)
  Proof: rg shows "type": "serving_endpoint" in the serving manifest and in template/appkit.plugins.json:486. The PR body says this was left out on purpose because serving calls the invocations URL, which a model service does not have.

Not required (below the gate)

• minor: The lister is a CLI drill-down in PARENT_CONTEXT_CHAINS (databricks ai-gateway list-model-services). The task asked for a workspace-client method plus an SDK_LISTERS entry, and the branch adds nothing under packages/shared/src/workspace-client. (packages/shared/src/cli/commands/registry/workspace-picker.ts:363)
  Proof: git diff --stat 34b41cc...HEAD has no workspace-client files.
• minor: PR feat(appkit): add model_service resource and use it in the agents plugin #705 is not a draft; the task asked for a draft PR. (PR #705)
  Proof: gh pr view 705 --json isDraft returned false.
• minor: adapterFromModelString now sends any dotted name to the AI Gateway, not only system.* names. That is broader than the task asked for; the PR documents it and gives a workaround. (packages/appkit/src/agents/databricks.ts:1015)
  Proof: Seen in the diff: startsWith("system.") became includes(".").

[MarioCadenas]

Review 11 · Pass · 1 pre-existing

Does the change do what the task asked? Yes. Gate: major and worse must be fixed.

The model_service resource, its uc_securable/MODEL_SERVICE/EXECUTE binding, the lister, and the agents plugin wiring are in place, and their tests pass. The serving plugin stays on serving_endpoint, which the human decided. This round only changes the lockfiles: every resolved URL is on registry.npmjs.org and none points at the internal mirror. CI on this commit was still running when I reviewed it.

Not required (there before this change)

• minor: The lockfile fix depends on the release bot's next template sync not re-pinning versions that are under the registry's 7-day block, so the template CI failure can come back. (template/package-lock.json, template/pnpm-lock.yaml)
  Proof: The agent says so itself, and the commit message confirms the bot owns these files.

[MarioCadenas]

Review 12 · Pass · 1 minor

Does the change do what the task asked? Yes. Gate: major and worse must be fixed.

The model_service feature is in place: schema, binding, lister/picker, doctor check, and agents wiring, with tests passing. The human decided the serving plugin stays on serving_endpoint. This round only re-resolves the template lockfiles; the sampled versions predate the 8-day cutoff and template/package.json is unchanged, but CI on this commit was still pending when I checked.

Not required (below the gate)

• minor: The lockfile fix holds only until the release bot's next template sync pins versions newer than the registry's cooldown, so the template CI failure can come back. (template/package-lock.json, template/pnpm-lock.yaml)
  Proof: Lockfiles were hand-resolved with a date cutoff and @swc/helpers was pinned by hand to 0.5.23; nothing in the sync process keeps that in place.