API — will developers adopt it?
Brief 113

API Versioning & Deprecation

How the API evolves without breaking the people who built on it — the versioning scheme, breaking-change discipline, and how deprecations are announced and retired.

VERSIONING.md4 phases7 lenses~2.7k chars

Free & open · no signup · read-only — it ends by asking · nothing leaves your machine

What it does

You are working inside this repo. Mission: judge how this API changes over time — whether it can add and evolve without breaking existing integrations, and whether deprecations are announced, dated, and migratable rather than sprung on people.

Read-only pass. Read the API surface, its versioning, and its change history; change nothing but the report file.

What it looks for

7 lenses it looks through

Phase 2 sweeps the codebase through every one of these, citing file and line for each finding.

1

Versioning scheme

a clear, consistent scheme (URL, header, or date) applied everywhere

2

Breaking-change discipline

a defined line for what counts as breaking, enforced not ad hoc

3

Backward compatibility

additive by default; old clients keep working

4

Deprecation process

how a deprecation is announced, signaled (headers, docs), and dated

5

Sunset & migration

a real timeline and a migration path, not an indefinite "deprecated"

6

Change communication

a changelog and notifications where consumers actually learn of changes

7

Undocumented surface

the fields and endpoints people depend on that were never meant to be public

The deliverable

What lands in your repo

One structured report at the repo root — or in reports/, if you keep one — the same shape every time, ready for a teammate — or the optional Studio — to act on.

VERSIONING.md
1
Current practice
the versioning and deprecation reality today
2
Breaking-change risks
the changes or habits that will break callers, by exposure
3
Policy
the versioning scheme, compatibility rules, and deprecation timeline to adopt
4
Signals
the headers, changelog, and notices that keep consumers informed
One file. Evidence-backed. It ends by asking before touching anything.
How it works

What it makes the agent do

Every Goal Prompt follows the same four steps, so results are consistent and repeatable — no matter which one you run.

1
Phase 1

Learn how it changes

Identify the versioning scheme, if any, and how consistently it is applied.

2
Phase 2

Audit through 7 lenses

Versioning scheme — a clear, consistent scheme (URL, header, or date) applied everywhere.

3
Phase 3

Curate

Rank by how many integrations a change would break and how little warning they'd get.

4
Phase 4

Report

Create VERSIONING.md at repo root.

Get started

Three ways to run this Goal Prompt

01 · COPY

Paste it in

Copy it and paste it into your agent inside the repo you want checked.

02 · INSTALL

As a slash command

Install the goal plugin once — two commands — then just type /goal:api-versioning.

1/plugin marketplace add GhostlyGawd/goal-prompts
2/plugin install goal@goal-prompts

Or install only this Goal Prompt as /goal-api-versioning:

curl -fsSL https://goal-prompts.vercel.app/install | BRIEF=113 sh
03 · AGENT

From an agent (MCP)

Let an agent fetch it mid-conversation, or pull the raw Goal Prompt by URL.

https://goal-prompts.vercel.app/raw/113.md
Transparency

The exact prompt

Nothing hidden — this is the whole Goal Prompt, verbatim. Read it in a minute, edit it, or copy it as-is.

Read the full brief (2,724 characters)
# Goal: API Versioning & Deprecation

You are working inside this repo. Mission: judge how this API changes over time — whether it can add and evolve without breaking existing integrations, and whether deprecations are announced, dated, and migratable rather than sprung on people.

Read-only pass. Read the API surface, its versioning, and its change history; change nothing but the report file.

## Phase 1 — Learn how it changes
- Identify the versioning scheme, if any, and how consistently it is applied.
- Look at recent changes: which were additive and which broke callers.
- Find how deprecations are currently signaled and communicated.

## Phase 2 — Audit through 7 lenses
1. **Versioning scheme** — a clear, consistent scheme (URL, header, or date) applied everywhere
2. **Breaking-change discipline** — a defined line for what counts as breaking, enforced not ad hoc
3. **Backward compatibility** — additive by default; old clients keep working
4. **Deprecation process** — how a deprecation is announced, signaled (headers, docs), and dated
5. **Sunset & migration** — a real timeline and a migration path, not an indefinite "deprecated"
6. **Change communication** — a changelog and notifications where consumers actually learn of changes
7. **Undocumented surface** — the fields and endpoints people depend on that were never meant to be public

## Phase 3 — Curate
- Rank by how many integrations a change would break and how little warning they'd get.
- For each gap, name the fix — a scheme, a compatibility rule, a deprecation header, a sunset policy.
- Separate a one-time cleanup from the ongoing policy that prevents the next break.

## Phase 4 — Report
Create `VERSIONING.md` at repo root:
1. **Current practice** — the versioning and deprecation reality today
2. **Breaking-change risks** — the changes or habits that will break callers, by exposure
3. **Policy** — the versioning scheme, compatibility rules, and deprecation timeline to adopt
4. **Signals** — the headers, changelog, and notices that keep consumers informed

Start the report with today's date. If `VERSIONING.md` already exists from a previous run, read it first and lead with what changed since.

## Rules
- Every consumer is code you cannot see; break it and you break trust silently
- A deprecation without a date and a migration path is just a warning nobody acts on
- No public API surface in this repo? Say so in a one-paragraph null report and stop — a null result is a valid finding.
- If a `reports/` directory exists at the repo root, write the report there instead of the root.
- Before asking, present the top findings as a ranked list in plain words
- Report only — end by asking which versioning changes to make first

House rules for this Goal Prompt

  • Every consumer is code you cannot see; break it and you break trust silently
  • A deprecation without a date and a migration path is just a warning nobody acts on
  • No public API surface in this repo? Say so in a one-paragraph null report and stop — a null result is a valid finding.
  • If a reports/ directory exists at the repo root, write the report there instead of the root.
  • Before asking, present the top findings as a ranked list in plain words
  • Report only — end by asking which versioning changes to make first
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