Add community/anthropics-buffa plugin v0.2.0

buffa is a zero-copy Rust Protobuf implementation with editions support
(2023/2024), no_std compatibility, and view types for borrowed field
access. Passes the protobuf conformance suite (5539 binary+JSON tests).

The plugin emits one .rs file per proto file using a flat naming
convention (`foo/v1/bar.proto` -> `foo.v1.bar.rs`), matching what BSR
expects. Module tree assembly is a separate `protoc-gen-buffa-packaging`
plugin in the same repo, not needed for BSR (which synthesizes lib.rs
server-side).

Crates: https://crates.io/crates/protoc-gen-buffa
Repo: https://github.com/anthropics/buffa

Author: iainmcgin

plugins/community/anthropics-buffa/source.yaml

@@ -0,0 +1,4 @@
+source:
+  github:
+    owner: anthropics
+    repository: buffa

plugins/community/anthropics-buffa/v0.2.0/.dockerignore

@@ -0,0 +1,2 @@
+*
+!Dockerfile

plugins/community/anthropics-buffa/v0.2.0/Dockerfile

@@ -0,0 +1,15 @@
+# syntax=docker/dockerfile:1.19
+FROM rust:1.91.1-alpine3.22 AS builder
+RUN apk add --no-cache musl-dev
+WORKDIR /app
+ENV CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse
+RUN --mount=type=cache,target=/usr/local/cargo/registry,sharing=locked --mount=type=cache,target=/root/target \
+    cargo install protoc-gen-buffa --version 0.2.0 --locked --root /app
+
+FROM gcr.io/distroless/static-debian12:latest@sha256:87bce11be0af225e4ca761c40babb06d6d559f5767fbf7dc3c47f0f1a466b92c AS base
+
+FROM scratch
+COPY --link --from=base / /
+COPY --link --from=builder /app/bin/protoc-gen-buffa /protoc-gen-buffa
+USER nobody
+ENTRYPOINT ["/protoc-gen-buffa"]

plugins/community/anthropics-buffa/v0.2.0/buf.plugin.yaml

@@ -0,0 +1,41 @@
+version: v1
+name: buf.build/community/anthropics-buffa
+plugin_version: v0.2.0
+source_url: https://github.com/anthropics/buffa
+description: Generates Rust message types with buffa, a zero-copy Protobuf implementation with editions support and no_std compatibility.
+output_languages:
+  - rust
+spdx_license_id: Apache-2.0
+license_url: https://github.com/anthropics/buffa/blob/v0.2.0/LICENSE
+registry:
+  cargo:
+    rust_version: "1.85"
+    deps:
+      # Runtime: wire format, Message trait, view types, JSON helpers.
+      # https://github.com/anthropics/buffa/blob/v0.2.0/buffa/Cargo.toml
+      - name: "buffa"
+        req: "0.2.0"
+        default_features: true
+        features:
+          - json
+      # Well-known types (Timestamp, Duration, Any, Struct, etc.).
+      # Generated code references these via the auto-injected
+      # extern_path mapping `.google.protobuf` -> `::buffa_types::google::protobuf`.
+      - name: "buffa-types"
+        req: "0.2.0"
+        default_features: true
+        features:
+          - json
+      # Generated code derives `::serde::Serialize` / `::serde::Deserialize`
+      # directly when json=true, so serde must be a direct dep.
+      - name: "serde"
+        req: "1"
+        default_features: true
+        features:
+          - derive
+  opts:
+    # Enable serde derives + proto3 JSON mapping helpers. Required for
+    # downstream plugins that need the Connect protocol's JSON codec.
+    - json=true
+    # Zero-copy view types. Default, but explicit for clarity.
+    - views=true