What is protobuf-schema-evolution?

A set of rules and checks for changing Protocol Buffer schemas safely. Protocol Buffers store structured data in a compact format, and this guidance covers saved app settings plus messages exchanged between Kotlin and Rust.

Use it before adding, reusing, or removing a field number in an app settings schema, or changing the diagnostics messages shared by Kotlin and Rust.

It helps prevent old saved settings from becoming unreadable or corrupted after an update. It also reduces failures caused by Kotlin and Rust disagreeing about message fields.

How po4yka/RIPDPI configures Claude Code and Codex

Reuse

Borrowing it

Nothing to install: this file belongs to po4yka/RIPDPI. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/po4yka/RIPDPI/main/.agents/skills/protobuf-schema-evolution/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/po4yka/RIPDPI

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/po4yka/ripdpi/protobuf-schema-evolution/github.svg)](https://agentmods.dev/skills/po4yka/ripdpi/protobuf-schema-evolution)

Your own site

<a href="https://agentmods.dev/skills/po4yka/ripdpi/protobuf-schema-evolution"><img src="https://agentmods.dev/badge/skills/po4yka/ripdpi/protobuf-schema-evolution/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/po4yka/ripdpi/protobuf-schema-evolution"><img src="https://agentmods.dev/badge/skills/po4yka/ripdpi/protobuf-schema-evolution.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,363 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00044	$0.01363
Opus 5.5	$0.00018	$0.00545
Sonnet 5.5	$0.00009	$0.00273
Haiku 4.5	$0.00004	$0.00136

Measured yesterday against content hash 3696d60943f5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

protobuf-schema-evolution scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/protobuf-schema-evolution/SKILL.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Protobuf Schema Evolution

Why This Matters

AppSettings is serialized as protobuf bytes and persisted on disk via Jetpack DataStore. When the app updates, new code must read bytes written by every older version. A field-number collision silently corrupts data -- the user loses their configuration with no error and no recovery path.

The diagnostics engine adds a second dimension: Kotlin and Rust exchange JSON wire messages whose schemas must stay in lockstep. A field mismatch causes silent data loss or deserialization failures at runtime.

AppSettings Proto

Schema: core/data/model/src/main/proto/app_settings.proto

Never trust a cached reserved-number list or highest-field-number in this skill, in a prior PR, or from memory -- both grow with every schema change and a stale number is exactly the silent-corruption risk this skill exists to prevent. Before assigning any new field number, run both of these against the live schema:

grep -n reserved core/data/model/src/main/proto/app_settings.proto
grep -oE '= [0-9]+;' core/data/model/src/main/proto/app_settings.proto | grep -oE '[0-9]+' | sort -n | tail -1

The first command prints every reserved block (there may be more than one, each with a numbers line and a names line); the second prints the highest field number currently declared anywhere in the file. Assign the next number strictly above that highest number, and confirm it does not fall inside any reserved range first.

Rules

Never reuse a field number. Proto3 identifies fields by number. If field 15 was desync_method and you assign 15 to something new, existing persisted bytes silently decode as the wrong field.
Reserve removed fields. Add both the number AND name to reserved. This makes protoc reject future reuse at compile time.
Use the next available number. Do not fill gaps from past removals.
Set defaults in AppSettingsSerializer. Every new field needs a default in AppSettingsSerializer.defaultValue (core/data/.../AppSettingsSerializer.kt). Proto3 zero-values (0, false, "") are implicit; if the real default differs (e.g., proxy_port = 1080), the serializer is the only place it gets set.

Read the full file on GitHub · 124 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

yesterday First seen · 124 lines · 44 tokens per session scan A 3696d60943f5

Subscribe to this mod's changes

protobuf-schema-evolution is a skill published in the GitHub repository po4yka/RIPDPI (85 stars, last pushed yesterday), licensed BSD-3-Clause. It adds 44 tokens to every session and 1,363 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-11-07.

Backend and APIs Kotlin and Swift Languages Rust android android-vpn anti-censorship censorship-circumvention deep-packet-inspection dns-over-https

protobuf-schema-evolution next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
protobuf-schema-evolutionpo4yka/RIPDPI	Skill	85	yesterday	BSD-3-Clause	A	44	Claude Code, Codex
ktor-patternsTalissonVitorino/kmp-ios-skills	Skill	16	2mo ago	MIT	A	96	Claude Code, Codex
retrofit-kotlinalmasumdev/awesome-kotlin-android-agent-skills	Skill	3	6mo ago	none	A	42	Claude Code, Codex
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RIPDPI: Skill for Claude Code