How to keep your docs site in sync when code changesHow to keep your docs site in sync when code changes

The short answer: to keep a docs site in sync when code changes, make every code change answer one question before it ships: "what did this change for the people using the product?" In practice that means four layers: generate what can be generated (API references, CLI help, config schemas), keep the docs in Git next to the code, make documentation part of the pull request review, and automate the detection of pages a change made wrong. The first three stop most drift. The fourth catches what people miss, which is the part that usually breaks.

Why docs drift in the first place

Documentation rarely goes out of date because nobody cares. It goes out of date because the change and the page live in different places, owned by different people, reviewed at different times.

A developer renames a configuration option. The code is updated and the tests pass. The old name still appears in the API reference, a quickstart, a troubleshooting article, and a blog post with a copyable example. Nobody decided to leave those pages wrong. Nobody knew they existed.

Drift has three common sources:

• Generated facts that were copied by hand. Parameter names, defaults, and response shapes pasted into prose instead of pulled from the source.
• Changes nobody flagged as user-facing. A refactor that quietly changes an error message, a default timeout, or the order of setup steps.
• Pages far from the change. Guides, tutorials, support articles, and marketing pages that mention a behavior without being "the docs for" that feature.

Each layer below targets one of these.

Layer 1: generate what can be generated

Anything with a machine-readable source of truth should be generated from it, not written by hand.

Content	Source of truth	How to keep it current
API reference	OpenAPI or GraphQL schema	Regenerate on every build
SDK reference	Type definitions and doc comments	Generate from the package on release
CLI reference	The CLI's own help output	Render from the command definitions
Configuration reference	JSON Schema or typed config	Generate tables from the schema
Code examples	Tested snippet files	Import snippets instead of pasting them

If your docs platform renders an OpenAPI spec directly, the reference updates the moment the spec does. Thally, for example, generates the API reference and its Try-It console from openapi.yaml at build time, so the reference cannot fall behind the spec it ships with.

Generation handles reference material well. It does nothing for the quickstart that walks through three of those endpoints in order, which is where layers 2 to 4 come in.

Layer 2: keep docs in Git, next to the change

When docs live in a separate editor with its own workflow, keeping them current depends on someone remembering to go there. When docs are MDX or Markdown in a repository, the documentation update can ride in the same pull request as the code, or in a linked PR that is reviewed at the same time.

Docs-as-code gives you:

• Review in one place. The reviewer sees the code diff and the docs diff together.
• History. git blame on a page tells you which change last touched it and why.
• Previews. A preview deployment per pull request lets reviewers read the updated page before it goes live.
• Rollback. A bad docs change is reverted the same way as a bad code change.

This is the model Thally, Docusaurus, and Mintlify share. Tools built around a hosted WYSIWYG editor can sync with Git, but the source of truth usually sits in the editor.

Layer 3: make documentation part of the pull request

Process catches a lot of drift when it is lightweight enough that people actually follow it.

• A PR template checkbox. "Does this change anything a user sees: API, CLI, config, errors, defaults, UI copy? If yes, link the docs change." It takes two seconds and prompts the right question at the right time.
• CODEOWNERS for docs-sensitive paths. Route changes to public API definitions, config schemas, and CLI commands to someone who owns the docs for that surface.
• Path-based reminders in CI. If a PR touches openapi.yaml or src/cli/** and no file under docs/ changed, post a comment or add a label. Keep it a nudge, not a hard block, or people will learn to work around it.
• Link and lint checks. Broken links and style drift are the easiest problems to catch automatically. Run a link checker and a prose linter such as Vale on every docs PR.

We walk through the CI side in detail in how to set up CI to trigger documentation updates on code changes.

Layer 4: automate impact detection

Layers 1 to 3 depend on someone recognizing that a change is user-facing and knowing where it is mentioned. That breaks down as the product grows. A single rename can touch pages that nobody on the PR has ever read.

This is the problem product-change tools are built for. Instead of relying on memory, they read the merged change, work out what it means for users, and search the documentation for pages that now contradict it.

Thally Track works this way:

1. You connect the product repositories that define your public surfaces (SDK exports, configuration schemas, CLI commands, API operations) and the repositories where customers read about the product.
2. When a pull request merges into a tracked repository, Track works out what changed for users and searches every connected surface for pages that now say otherwise.
3. For each affected page it drafts an update and opens a pull request with the evidence: the diff that caused it, why the page is affected, and the proposed change.
4. A person on your team reviews, edits, and merges it. If nothing needs changing, Track says so and opens nothing.

You can also run it before merge. Adding a docs-preview label to an open pull request drafts the docs while the code is still in review, so reviewers see both together.

The important property is that automation proposes and people decide. Automated docs changes that publish without review trade one kind of inaccuracy for another. For more on the post-merge flow, see how to automatically update documentation after a pull request merges.

A checklist you can adopt this week

1. Generate your API reference from the spec instead of maintaining it by hand.
2. Move docs into Git if they are not there already, with a preview deployment per PR.
3. Add one docs question to your PR template.
4. Add a CI job that comments when public-surface paths change without a docs change.
5. Run a link checker on every docs build.
6. Try impact detection on your own history: the Track demo reads your last five merged pull requests and shows which pages each one affected, with no account required.

When a manual process is enough

If you have one product repository, one docs site, and a team small enough that the person writing the code also writes the docs, layers 1 to 3 will keep you in good shape. Automation earns its place when changes land faster than any one person can read them, when docs span several repositories and surfaces, or when you have already shipped a page that was wrong for weeks before anyone noticed.

Sources and verification

Thally capabilities were checked against the current product repository, documentation, and the Track overview. Checked September 24, 2026. Read our editorial policy for how we write and review guides.