Safety-Assured Blocks

When you’ve manually verified an operation is safe, use safety-assured comment blocks to bypass checks:

-- safety-assured:start
ALTER TABLE users DROP COLUMN deprecated_column;
ALTER TABLE posts DROP COLUMN old_field;
-- safety-assured:end

All statements between the start and end markers are skipped by all checks — both built-in and custom.

Disable Specific Checks for One Migration

When only one check is known to be acceptable for a migration, disable that check by name instead of suppressing the whole statement:

-- diesel-guard:disable AddColumnCheck
ALTER TABLE users ADD COLUMN admin BOOLEAN DEFAULT FALSE;

Other checks still run on the same migration. For example, the statement above can still be flagged by IdempotencyAlterCheck if it is missing IF NOT EXISTS.

Disable multiple checks with a comma-separated list:

-- diesel-guard:disable AddColumnCheck, IdempotencyAlterCheck
ALTER TABLE users ADD COLUMN admin BOOLEAN DEFAULT FALSE;

For Diesel directory migrations, you can also put migration-scoped disables in that migration’s metadata.toml:

disable_checks = ["AddColumnCheck"]

Multiple Blocks

-- safety-assured:start
ALTER TABLE users DROP COLUMN email;
-- safety-assured:end

-- This will be checked normally
CREATE INDEX users_email_idx ON users(email);

-- safety-assured:start
ALTER TABLE posts DROP COLUMN body;
-- safety-assured:end

When to Use Safety-Assured

Only use when you’ve taken proper precautions:

1. For DROP COLUMN:

   • Stopped reading/writing the column in application code
   • Deployed those changes to production
   • Verified no references remain in your codebase

2. For other operations:

   -- safety-assured:start
   -- Safe because: table is empty, deployed in maintenance window
   ALTER TABLE new_table ADD COLUMN status TEXT DEFAULT 'pending';
   -- safety-assured:end
   

Error Handling

diesel-guard will error if blocks are mismatched:

Error: Unclosed 'safety-assured:start' at line 1

Rules:

• Blocks cannot be nested — a second start before end is an error
• Unclosed blocks are errors
• Unmatched end directives (without a preceding start) are errors
• The directives are case-insensitive