buf-validated Protocol Buffers authoring — write or modify .proto files with pre-edit analysis of wire-compat constraints, style conventions, and coordinated codegen + downstream consumer updates. Use for any non-trivial .proto edit (new message/field/rpc, type change, deprecation).
Installation
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buf-validated Protocol Buffers authoring — write or modify .proto files with pre-edit analysis of wire-compat constraints, style conventions, and coordinated codegen + downstream consumer updates. Use for any non-trivial .proto edit (new message/field/rpc, type change, deprecation).
Proto Authoring Skill
Write and modify .proto files as a structured workflow — analogous to go-modify. Treat the .proto as the source of truth and generated Go/TS bindings as derived artifacts that must stay in lock-step.
When to Use This Skill
Use when:
Adding or removing a message, field, enum value, or RPC
Changing a field's type, label, or number
Splitting or merging messages
Introducing a new .proto file or package
Any change that will regenerate *.pb.go / *_grpc.pb.go / generated TS types
Skip when:
Comment-only edits
Formatting / import ordering with no semantic change
Prerequisites
buf, protoc, or the project's codegen task available (check buf.gen.yaml, Makefile, mise.toml, package.json)
Generated output directories are writable and not in .gitignore if the repo commits generated code
PHASE 1: Pre-Edit Analysis
Read the entire target .proto file (and its import chain one level deep) before any edit.
File-level constraints checklist
syntax — proto2 vs proto3 changes defaults (optional/required, zero values)
package + option go_package / option java_package — generated path is derived from these
Existing field numbers — note the highest number; reserved ranges; never reuse a removed field number or name (use reserved)
Naming conventions in the file: snake_case field names, PascalCase messages, SCREAMING_SNAKE_CASE enum values, enum zero value suffix (_UNSPECIFIED)
Wire-compat history — if this proto is on a network or persisted, deletions/renumberings are breaking. Mark removed fields with reserved <num>; and reserved "name";
TS package(s) importing the generated client (often @<scope>/<api>-ts)
Any non-Go/TS consumer (Python, Java)
PHASE 2: Planning
Classify the edit:
Additive (new field with new number, new optional message, new RPC) → wire-compatible
Renaming (field/message name only, number unchanged) → wire-compatible but breaks source consumers
Breaking (type change, number change, removal, label change) → requires migration plan
For breaking changes: write the migration in .notes/ before editing (new field + dual-write + flip + remove).
Pick field numbers explicitly. Use 1–15 for hot fields (1-byte tag), 16+ for cold.
List the exact codegen command(s) to run after the edit.
Execution Rule
Never rm -rf a generated directory. Re-run codegen in place. If output looks stale, delete only files the generator owns and re-emit. Generated files belong in the same commit as the .proto change.
Never pause mid-task to ask "shall I proceed?" once intent is clear. Only stop on destructive ambiguity (e.g., the field number you want is in a reserved range).
PHASE 3: Implementation
Step 3.1: Edit the .proto
Use Edit tool. Match existing style. For removals, add reserved entries in the same edit.
Step 3.2: Lint
buf lint # or: buf lint <module>
buf breaking --against '.git#branch=main'# if the project tracks wire compat
Fix all findings. buf breaking failures are not optional unless the migration plan from Phase 2 explicitly accepts the break.
Step 3.3: Regenerate
Run the project's codegen task (look it up — do not guess):
buf generate # most projects
mise run gen # if a mise task exists# or the Makefile target the repo defines
Verify the generator wrote new files. If output is empty, the plugin config is wrong — fix buf.gen.yaml, do not delete the output dir.
Step 3.4: Update Consumers
For each downstream Go/TS package identified in Phase 1:
Apply the same naming change (rename, new field accessor)
For new optional fields: existing call sites compile unchanged
For removed/renamed fields: every reference must be updated in this same change
Use mcp gopls go_symbol_references (Go) and ast-grep / ccc (TS, polyglot) to find call sites.
Step 3.5: Build & Test
go build ./...
go test ./<affected>/...
pnpm -r build # or the project's TS build
PHASE 4: Commit Hygiene
One commit contains:
The .proto change
All regenerated files
All consumer updates required to compile
Never split .proto from its generated artifacts across commits — intermediate states won't build.
Required Tools
buf (lint + breaking + generate) or project codegen task
Edit tool for the .proto
mcp gopls go_symbol_references for Go consumers
ast-grep / ccc for cross-language reference tracking
Final Report
Edit class: additive / renaming / breaking
Field numbers used / reserved
buf lint and buf breaking results
Generated files: list paths
Consumers updated: files + symbols
Build/test: results per package
Autoresearch rules
Eval checklist:
Did the agent read the full .proto and its imports before editing?
Was buf lint (or equivalent) run and clean?
Was buf breaking run for projects with wire-compat history?
Were generated files committed alongside the .proto?
Were zero rm -rf operations performed on generated dirs?
Did all downstream Go/TS consumers build after the change?
Test inputs:
"Add a repeated string tags = 4 field to Tree message"
"Rename GetNode RPC to FetchNode across api.proto and TS client"
"Deprecate legacy_id field and add id as bytes"
Can change: pre-edit checklist, lint commands, consumer-discovery steps, generator invocation
Cannot change: no-rm -rf rule, same-commit rule for proto + generated, lint-before-generate order
Min sessions before eval: 5
Runs per experiment: 3
