Annotating Code

Requirement references link your source code back to the specification. They're written as comments using the syntax PREFIX[VERB requirement.id].

Basic syntax

rust

// r[impl auth.login]
fn login(username: &str, password: &str) -> Result<Token> {
    // ...
}

The verb defaults to impl when omitted, so these are equivalent:

rust

// r[impl auth.login]
// r[auth.login]

You can add text after the closing bracket — it's ignored by the parser:

rust

// r[impl auth.login]: handles credential validation

Verbs

Verb	Meaning	Use for
`impl`	Implements the requirement	Production code that fulfills the spec
`verify`	Tests/verifies the requirement	Test code that asserts correct behavior
`depends`	Strict dependency	Code that must be rechecked if the requirement changes
`related`	Loose connection	Related code shown during review

If no verb is given, impl is assumed.

impl

Marks code that implements a requirement:

rust

// r[impl channel.lifecycle.open]
fn open_channel(&mut self, id: u32) -> Result<()> {
    // ...
}

verify

Marks test code that verifies a requirement:

typescript

// r[verify channel.lifecycle.open]
test('channel must be opened before sending data', () => {
    const channel = new Channel();
    expect(() => channel.send(data)).toThrow('not open');
});

depends

Marks code with a strict dependency on a requirement — it must be reviewed whenever that requirement changes:

python

# r[depends auth.crypto.algorithm]
def hash_password(password: str) -> str:
    return bcrypt.hashpw(password.encode(), bcrypt.gensalt())

Marks a loose connection, surfaced when reviewing related code:

swift

// r[related user.session.timeout]
func cleanupExpiredSessions() {
    sessions.removeAll { $0.isExpired }
}

Language examples

Tracey extracts annotations from comments in all major languages via tree-sitter:

Rust — line, doc, and block comments:

rust

// r[impl auth.login]
/// r[impl auth.login]
//! r[impl auth.login]
/* r[impl auth.login] */

TypeScript / JavaScript:

typescript

// r[impl api.response-format]
/* r[verify api.response-format] */

Python:

python

# r[impl auth.validation]

Go:

// r[impl stream.priority]
/* r[verify stream.priority] */

Swift:

swift

// r[impl session.timeout]

Java:

java

// r[impl database.connection]
/** r[verify database.connection] */

C / C++:

// r[impl buffer.allocation]
/* r[verify buffer.allocation] */

Multiple annotations per function

A single function can implement multiple requirements:

rust

// r[impl auth.validation]
// r[impl auth.rate-limiting]
fn validate_with_rate_limit(credentials: &Credentials) -> Result<()> {
    check_rate_limit(credentials.ip)?;
    verify_credentials(credentials)?;
    Ok(())
}

Multiple functions per requirement

A single requirement can be implemented across multiple functions. Adding a trailing comment can help clarify:

rust

// r[impl database.connection]
fn create_pool(config: &DbConfig) -> Pool {
    // connection pooling
}

// r[impl database.connection]
fn close_connection(conn: Connection) {
    // connection lifecycle
}

Test files

If your config uses the test_include field to designate test files, those files may only contain verify annotations. Using impl in a test file is an error. See Configuration for details.

Ignore directives

Sometimes source code mentions requirement syntax in documentation, test fixtures, or string literals where it shouldn't be extracted. There are several ways to suppress extraction.

Backticks

Annotations inside backticks in comments are ignored:

rust

// This is `r[impl not.an.annotation]`, just a comment

Ignore next line

rust

// @tracey:ignore-next-line
// This mentions r[impl auth.login] but it won't be extracted

Ignore block

rust

// @tracey:ignore-start
// These fixtures contain r[impl auth.login] and r[impl api.format]
// but they're just test data, not actual annotations
// @tracey:ignore-end

Ignore blocks must not nest. An unclosed @tracey:ignore-start is reported as an error during validation.

Multiple specs

When your project implements multiple specs (each with a different prefix), use the appropriate prefix for each:

rust

// r[impl auth.login]          // internal spec (prefix "r")
// h2[impl stream.priority]    // HTTP/2 spec (prefix "h2")

The prefix routes the annotation to the correct spec. See Configuration for setting up multiple specs.