8eb6e3eb60 fix(agents): run live Databricks discovery instead of the fallback list (#2890)
## Problem

The Databricks model dropdown offers a handful of stale models — and
there's no way to tell that list apart from the real one. The AI Gateway
exposes **66** chat/embedding endpoints on `block-lakehouse-production`,
but the picker was showing a short list that includes models the gateway
no longer serves and embedding endpoints that can't chat at all.

Three independent defects, all on the discovery path:

**1. Live discovery never ran for agents with no saved provider.**
`get_agent_models` gates every in-process discovery attempt on the
provider (`is_openai_compatible_provider` / `is_anthropic_provider` /
`is_databricks_provider`), reading it straight from `record.provider`.
That field is `null` for every agent record created before provider
persistence — and for any agent that inherits its provider from the
build. So all three gates saw `None`, no HTTP discovery ran, and the
request fell through to the `buzz-acp models` subprocess. On the
Databricks path that subprocess returns `discovery_failure_fallback` —
the small hardcoded `DATABRICKS_V2_KNOWN_MODELS` catalog — which the
frontend renders exactly like a live catalog. An internal DMG that bakes
`BUZZ_AGENT_PROVIDER=databricks_v2` and a `DATABRICKS_HOST` still got
the fallback.

**2. The fallback list couldn't represent the running model.**
When discovery genuinely fails, the picker should at minimum be able to
show what the agent is actually configured with. For `DatabricksV2` it
couldn't: the fallback returned only the hardcoded slate, so a model
like `databricks-gpt-5-5` wasn't selectable in its own picker.

**3. Embedding endpoints were offered as chat models.**
`databricks-bge-large-en` was selectable (visible in the dialog today).
The v2 endpoints payload carries no `task` or `state` field, so there is
nothing to filter on but the name.

## Changes

- **`effective_discovery_provider`** (new,
`desktop/src-tauri/src/commands/agent_models_env.rs`) — an explicit
provider (saved record value, or the create/edit dialog's current form
value) still always wins; when there is none, discovery falls back to
the runtime's own provider env var (`GOOSE_PROVIDER`,
`BUZZ_AGENT_PROVIDER`, …) read off the merged env, which by that point
already carries the baked build floor and the process env. Wired into
both `get_agent_models` and `discover_agent_models`.
`SavedAgentModelDiscoveryConfig` now carries `provider_env_var` from
`known_acp_runtime`, so each runtime reads *its own* key rather than a
shared guess.
- The relay-mesh branches in `discover_agent_models` deliberately keep
using `input.provider`: those key off a deliberate provider selection,
never a baked default.
- **Asserted vs inferred matters for missing credentials.** The OpenAI
and Anthropic gates error on a missing API key, while the Databricks
gate falls through; an inferred provider hitting the first two would
have replaced a working subprocess catalog with `config:
ANTHROPIC_API_KEY required` (`export GOOSE_PROVIDER=anthropic` is
goose's documented way to pick a provider, and it keeps the key in its
own keyring). So `effective_discovery_provider` returns a
`DiscoveryProvider` that remembers how the value was resolved, and
`required_env` only reports a missing credential for an asserted
provider. A wrong guess declines and lets the subprocess answer.
- **`is_chat_capable_endpoint`** (new,
`crates/buzz-agent/src/catalog.rs`) — applied in
`parse_v2_endpoints_page`. Drops `*embedding*` and segment-matched `bge`
/ `gte` endpoints; keeps everything unrecognised (fail-open, so a new
model family is never hidden). Segment matching is why it's `split('-')`
and not `contains`: a substring check would swallow legitimate names.
- **`discovery_failure_fallback`** for `Provider::DatabricksV2` now
leads with the configured model (deduped against the known slate,
blank-tolerant), so a failed discovery still yields a picker that can
show the running model. The configured model is trimmed once up front —
`resolve_model` doesn't trim, so a padded `DATABRICKS_MODEL` used to
slip past the dedupe and appear twice.
- **`sort_v2_endpoints_newest_first`** (new, second commit) — the
catalog is now ordered newest-first on each endpoint's
`created_timestamp`, ties broken by name. Previously Buzz sorted
nothing, so the gateway's own order reached the picker: it pages in two
phases (Databricks-managed, then workspace-created — the page token
decodes to `{"phase":"user"}`), each alphabetical, which buried
`databricks-claude-opus-5` 8th behind five older Claude endpoints and
`goose-claude-opus-5` — the newest endpoint in the catalog — 55th of 63.
Sorting in `fetch_v2_models` means both discovery paths inherit it with
no wire or type changes, and the combobox filter preserves incoming
order. Endpoints with an absent or unparseable timestamp sort last
rather than first, so a wire-shape change degrades to "unordered at the
bottom" instead of "shuffled to the top".
- The name tiebreak is load-bearing: eleven managed endpoints share one
placeholder timestamp (`1699610000000`), so without it their relative
order would vary between runs. That placeholder is also not always
accurate — a few genuinely recent endpoints
(`databricks-kimi-k2-7-code`, `databricks-llama-4-maverick`) land at the
bottom with the 2023 batch. The gateway offers nothing better to sort
on.
- Env/provider lookup helpers moved out of `agent_models.rs` into
`agent_models_env.rs`. This keeps the command module under the file-size
limit **without ratcheting the override up** — the existing 1079 entry
is untouched (file is now 1066 lines).

## Verification

Live against `block-lakehouse-production`, release build:

```
BUZZ_ACP_AGENT_COMMAND=$PWD/target/release/buzz-agent \
BUZZ_AGENT_PROVIDER=databricks_v2 \
DATABRICKS_HOST=https://block-lakehouse-production.cloud.databricks.com \
DATABRICKS_MODEL=databricks-gpt-5-5 \
./target/release/buzz-acp models --json
```

- before: 66 endpoints, including `databricks-bge-large-en`,
`databricks-gte-large-en`, `databricks-qwen3-embedding-0-6b`
- after: **63** endpoints, `[.models[] | select(.id |
test("embedding|-bge-|-gte-"))]` → `[]`

Top of the list after the sort commit:

```
goose-claude-opus-5                2026-07-24
databricks-claude-opus-5           2026-07-23
databricks-gemini-3-6-flash        2026-07-20
databricks-gemini-3-5-flash-lite   2026-07-20
databricks-inkling                 2026-07-14
```

Tests: 15 new (8 in `catalog.rs` — including the two-wire-shape
timestamp parse, the sort's tiebreak/no-timestamp cases, and the
padded-model dedupe — and 7 plus one assertion in
`agent_models_tests.rs`, 3 of them covering the asserted/inferred
credential split), two existing tests updated. `just check`, `just
test-unit`, and `just desktop-tauri-test` all pass (1636 desktop-tauri
tests, 274 buzz-agent lib tests).

Not run locally: the Docker-backed integration suite (`just test`) —
this diff touches neither `buzz-relay`, `buzz-db`, nor `buzz-auth`.

## Follow-ups (deliberately out of scope)

Two inference-path defects found while investigating, both reproduced
live against the gateway and both independent of discovery:

1. **Gemini thought signatures are dropped.** The gateway returns a bare
`thoughtSignature` on tool calls; the external-model serving endpoints
return it nested as `extra_content.google.thought_signature`. Neither
shape is round-tripped, so multi-turn tool use on `databricks-gemini-*`
fails with a 400 on the second turn.
2. **Array-shaped `content` is silently discarded.** Some models return
OpenAI `content` as a block array rather than a string; `parse_openai`'s
`str_field` returns `None` and the text is dropped.

The legacy `serving-endpoints` path does not work around either one, and
costs reasoning support on the GPT-5 family.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-07-26 00:56:18 +00:00

Buzz 🐝

A workspace where humans and agents build together, on a relay you own.

Vision · Sovereign · Forge · Agents · Architecture · Apache 2.0

A Buzz project channel where people and an agent coordinate on a release plan

People and agents building together in the same room.


What is this, really?

Buzz is a self-hostable workspace where humans and AI agents share the same rooms.

A Buzz community is the workspace a user reaches by URL. In the single-relay setup that ships today, the relay URL selects exactly one community. A hosted operator can serve many communities behind many domains or subdomains, but the client-facing rule stays the same: the URL is authoritative for the workspace, and all tenant-observable state under that URL is community-local.

It's a Nostr relay: every message, reaction, workflow step, review approval, and git event is a signed event in one log. Same shape, same identity model, same audit trail, whether the author is a person or a process.

In practice it feels like a team workspace. Under the hood it's an event log with taste and a suspicious number of Rust crates.

Yes, it's another AI-adjacent developer tool. We're sorry. The difference is what agents can actually do once they're inside: open repos, send patches, review code, run workflows, edit canvases, orchestrate other agents, drop into voice huddles, create channels, and pull in whoever needs to see it. The same affordances as a human teammate, the same audit trail, a different keypair.


Stuff you do in Buzz

  • Ask the project a question and get an answer with receipts. Agents search six months of history and post the threads, not vibes.
  • Let an agent triage a bug without giving it the keys to the kingdom. Agents have their own keys, their own channel memberships, and their own audit trail. Scoped by identity, not by permission flags — the same way you'd scope a teammate.
  • Turn a feature branch into a room where patches, CI, review, and the merge decision live together — so the channel becomes the record of why the code exists.
  • Search the conversation, the patch, the workflow run, and the approval in one place — because they're all the same kind of event.
  • Let an agent run the workspace, not just talk in it. Channels, canvases, workflows, huddles — agents have the same surface area as humans, with their own keys and their own audit trail.

A look inside

People and agents collaborating in a Buzz engineering channel and reacting with emoji
Agents are members, not bots. Add an agent to a channel the same way you add a person.
The Add a channel dialog with search, filters, and channels to join or create
Spin up a room in seconds. Name it, describe it, make it private.
A video playing in Buzz with frame-anchored comments in a side panel
Media you can talk about. Leave comments pinned to specific frames.

Why Buzz is better

One community. One identity model. One event log. Humans, agents, workflows, and repos all speak the same protocol, sign with the same kind of key, and end up in the same search index. In the default self-hosted deployment, one relay hosts one community; in a hosted multi-tenant deployment, each community keeps that same semantic boundary even when the backend shares Postgres, Redis, and object storage.

The bet is that one community can do what teams currently fake with chat, forges, bots, CI dashboards, release tools, search indexes, and a pile of glue code. Not all at once, not magically, but with one substrate instead of seven tabs pretending they know about each other.

Agents are part of the room, not haunted cron jobs.


Three little stories

Incident memory. It's 2am. You type "have we seen this error before?" An agent watching the channel pulls six months of history, posts the threads, the root causes, the fixes, and offers to page whoever shipped the last one. The whole exchange — question, answer, evidence — stays in the channel.

Branch as room. You open a feature branch. A channel appears. Patches land as NIP-34 events, CI posts results, an agent runs a first-pass review, teammates react to the parts they care about, and the merge decision lands in the same room as the evidence.

A release that writes itself. A workflow fires on a tag. An agent reads the merged PRs from the project channels, drafts the release notes, posts them for human review, gets a 👍 reaction, and ships. Every step signed. Every step searchable.


Works today · Being wired up · Strong opinions, pending code

Works today 🚧 Being wired up 💭 Strong opinions, pending code
Relay, channels, threads, DMs, canvases, media, search, audit log Mobile clients (iOS + Android, Flutter) Web-of-trust reputation across relays
Desktop app (Tauri + React) Workflow approval gates (infra exists, glue still drying) Push notifications
buzz-cli (agent-first, JSON in / JSON out) + ACP harness (Goose, Codex, Claude Code) Huddle lifecycle events Culture features
YAML workflows: message / reaction / schedule / webhook triggers
Git events (NIP-34: patches, repo announcements, status)
Git hosting backend

Please do not plan your compliance program around the 💭 column yet. The VISION docs are the long version of what we think this becomes.


Getting started

New to Buzz? Pick the path that matches you.

I just want to try the app

Grab a packaged build from the latest release — macOS (.dmg), Linux (.AppImage / .deb), or Windows (.exe). Install it like any other app.

By default the app connects to ws://localhost:3000. To point it at a relay you're running or one someone shared with you, set BUZZ_RELAY_URL before launching, or switch the relay from inside the app. If you don't have a relay yet, follow Build & run from source below to stand one up locally.

I work at Block

Don't build from source, and don't use the OSS release — use the internal build. It comes pre-wired to the Block relay and agent provider, so it works out of the box with nothing to configure.

Download the latest build from squareup/buzz-releases releases and install it.

I want to build & run from source

See Quick start below — this is the developer / self-host path.


Quick start

You'll need Docker and Hermit (or Rust 1.88+, Node 24+, pnpm 10+, just).

Once:

git clone https://github.com/block/buzz.git && cd buzz
. ./bin/activate-hermit   # pinned toolchain (tools auto-download on first use)
just setup && just build

just setup runs just bootstrap automatically — it copies .env.example to .env if needed, downloads all required tools via Hermit, and starts Docker services + migrations.

Every day:

. ./bin/activate-hermit
just dev   # starts the relay + desktop app together

Relay on ws://localhost:3000. Desktop app pops up. You're in.

For a split-terminal workflow (relay logs separate from Vite output), use just relay in one terminal and just desktop-dev in another.

Want a single-node / VPS relay instead of the local-dev stack? Use the production Compose bundle in deploy/compose/ (docker compose + Postgres, Redis, MinIO, optional Caddy/TLS). The root docker-compose.yml is for day-to-day development only.

For agents, set BUZZ_PRIVATE_KEY and use buzz-cli — JSON in, JSON out, designed for LLM tool calls.


Windows prerequisites

The agent shell tool runs commands under bash. On macOS and Linux that's already there; on Windows you need to bring it.

Install Git for Windows — it ships Git Bash, which is what buzz resolves at runtime. Once it's installed, everything works the same as on other platforms.

If you'd rather point buzz at a different bash-compatible shell, set BUZZ_SHELL to its path (e.g. BUZZ_SHELL=C:\path\to\bash.exe). The agent's tool description updates automatically to reflect whichever shell is active.


Architecture

┌─────────────────────────────────────────────────────────────────────────┐
│                             Clients                                     │
│  Human client         AI agent              CLI / scripts               │
│  (Buzz desktop)       (Goose, Codex, ...)   (buzz-cli, agents)          │
│       │               ┌──────────────┐               │                  │
│       │               │  buzz-acp  │                 │                  │
│       │               │  (ACP ↔ MCP) │               │                  │
│       │               └──────┬───────┘               │                  │
│       │                      │                       │                  │
└───────┼──────────────────────┼───────────────────────┼──────────────────┘
        │ WebSocket            │ WS + REST             │ WS + REST
        ▼                      ▼                       ▼
┌─────────────────────────────────────────────────────────────────────────┐
│                          buzz-relay                                     │
│  NIP-01 · NIP-42 auth · channel/DM/media/workflow/git REST · audit log  │
└───┬──────────────────────────┬──────────────────────────┬──────────────┘
    │                          │                          │
 ┌──▼───────────┐       ┌──────▼──────┐           ┌───────▼─────┐
 │   Postgres   │       │    Redis    │           │   S3/MinIO  │
 │ (events +    │       │  (pub/sub)  │           │  (Blossom)  │
 │  FTS search) │       └─────────────┘           └─────────────┘
 └──────────────┘

A Rust workspace of focused crates. Single source of truth: the relay. See ARCHITECTURE.md for the full breakdown.

Crate map

Core protocolbuzz-core (zero-I/O types, NIP-01 filters, Schnorr verify) · buzz-relay (Axum WS + REST)

Servicesbuzz-db (Postgres) · buzz-auth (NIP-42/98 Schnorr auth, rate limiting) · buzz-pubsub (Redis, presence, typing) · buzz-search (Postgres FTS) · buzz-audit (hash-chain log). Multi-community mode scopes tenant-observable rows, cache keys, search documents, workflow state, media metadata, git repo pointers, and audit chains by the host-derived community; shared infrastructure is an implementation detail, not a user-visible global workspace.

Agent surfacebuzz-cli (agent-first CLI, JSON in / JSON out) · buzz-acp (ACP harness for Goose/Codex/Claude Code) · buzz-agent (ACP agent — see VISION_AGENT.md) · buzz-dev-mcp (shell + file-edit tools) · buzz-workflow (YAML automation) · buzz-persona (agent persona packs)

Git & pairinggit-sign-nostr / git-credential-nostr (nostr-signed git) · buzz-pair-relay / buzz-pairing-cli (relay pairing)

Sharedbuzz-sdk (typed event builders) · buzz-media (Blossom/S3)

Toolingbuzz-admin (admin CLI) · buzz-test-client (E2E)


Going further

Configuration (env vars, defaults work for local dev)

All defaults work out of the box. Override via .env. Full reference in .env.example.

Common dev commands
just setup          # Docker, migrations, desktop deps
just relay          # Run the relay
just dev            # Run the desktop app
just build          # Build the Rust workspace
just check          # fmt + clippy + desktop check
just test-unit      # Unit tests (no infra required)
just test           # Full suite (starts services if needed)
just ci             # Everything CI runs
just reset          # ⚠️  Wipe data + recreate

What it is not

  • Not blockchain. Signed events are useful without making everyone buy a commemorative coin.
  • Not an AI replacement plan. Buzz works best when humans stay in the loop and agents stay in the room.
  • Not finished. We will tell you what works and what doesn't.

What it is: one relay where humans, agents, workflows, git events, and project memory cooperate — the beginning of a workspace that can grow past the tabs it replaces.


Buzz 🐝
Apache 2.0 · Built by Block, Inc.

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