CLI.

Seven commands. Small, scriptable, friendly to coding agents. None open a browser. None ask you to log in.

Run dif from the repo root or any descendant. It walks upward until it finds dif/config.yaml. Every command takes --json as a global flag for machine-readable output. Exit codes are documented per command; 0 means success, non-zero means a specific kind of failure you can branch on in CI.

Run dif --help for the auto-generated overview.

$dif init

Scaffold a dif/ workspace in the current directory. Refuses to clobber existing dif-owned files without --force.

Flags

Example

$dif init
✓ wrote dif/config.yaml
✓ created dif/experiments/{active,concluded}/
✓ created dif/surfaces/home.md
✓ created dif/audiences/{locale,device_type}.ts
✓ added dif guidance to CLAUDE.md, AGENTS.md, .cursorrules

The agent files get a managed dif block; existing content around it is preserved. Pass --no-agent-files to skip them entirely.

Exit codes

invarianta fresh dif init followed by dif validate and dif build passes with zero experiments.

$dif new

Draft a new experiment file. Reads up to three prior learnings from the surface and embeds them in the brief template as an HTML comment.

Flags

The draft starts with control and variant_a at 50/50 and today's date.

Example

$dif new checkout-cta-v3 --surface checkout
→ reading dif/surfaces/checkout.md
  found 3 prior learnings
→ drafted dif/experiments/active/checkout-cta-v3.md
  status: draft, owner: ada@acme.dev

Exit codes

invariantthe file dif new writes parses cleanly with dif validate.

$dif validate

Run every check against the workspace. Collects all errors and warnings in one pass (no fail-fast), so the report shows everything wrong at once. Writes nothing.

The validator reads:

• dif/config.yaml;
• every .md in dif/experiments/active/ and concluded/;
• every .md in dif/surfaces/;
• the resolver filenames in dif/audiences/;
• .js / .jsx / .ts / .tsx source for dif("<id>", ...) call sites (skipping .git, node_modules, target, dist, build, and dif/).

Checks, in order:

1. Frontmatter parses; required fields present. (E001)
2. owner is a syntactically valid email. (E003)
3. surface resolves to a loaded surface file. (E004)
4. Variant weights sum to 100. (E005)
5. Every audience attribute is declared in dif/config.yaml. (E006)
6. Every declared attribute has a resolver in dif/audiences/. (E008)
7. Same-surface experiments share an exclusion_group or have provably-disjoint audiences. (E007)
8. Every dif("<id>", ...) call site maps to an active experiment. (W001, warning)

Every diagnostic code is documented on troubleshooting. --schema-only is reserved for a future fast editor path; today it runs the same full suite.

Example

$dif validate
✓ all checks passed

$dif validate
error E003 dif/experiments/active/bad.md:1:1: `owner` is not a valid email: `not-an-email`
  help: Use `name@example.com` format.
error E008 dif/config.yaml: attribute `plan` has no resolver
  help: Create `dif/audiences/plan.ts` or run `dif scaffold-audiences`.

✗ 2 error(s), 0 warning(s)

Exit codes

$dif build

Run validate, then compile the runtime artifacts and the agent context file. Aborts before writing if validation fails.

Flags

Outputs

• <out>/client.ts: registers each active experiment with the SDK by side effect. Deterministic: identical inputs produce byte-identical output.
• <out>/audiences.ts: the attributes() helper, importing only the resolvers referenced by active experiments. Also deterministic.
• dif/context.json: the agent context file. Carries a generation timestamp (so it churns on every build) plus a summary of every active experiment, each surface's most recent learning, and project conventions.

Example

$dif build
✓ validated 1 active experiment
✓ client    → dif/generated/client.ts
✓ audiences → dif/generated/audiences.ts
✓ context   → dif/context.json

Exit codes

invariantclient.ts and audiences.ts compile under tsc --strict and are byte-identical for identical inputs.

$dif qa

Trace one user's assignment chain across every active experiment, and optionally mint a preview link. No exposure events are fired; qa runs entirely against the loaded workspace.

Flags

Example

$dif qa --user u_8131
trace u_8131:
  • checkout-cta-v2 → variant_a (bucket 7993)

$dif qa --force checkout-cta-v2=variant_a --preview-url https://staging.example.com/checkout
trace (synthetic user):
  • checkout-cta-v2 → variant_a (forced)
preview: https://staging.example.com/checkout?_dif=checkout-cta-v2%3Dvariant_a

The preview URL carries a _dif query parameter encoding the forces. The browser SDK and framework adapters read it and persist the force in a session cookie, so you can share a screenshot or hand the link to a teammate.

Outcomes

• variant (bucket N): bucketed normally; the SDK would fire an exposure for this assignment.
• variant (forced): picked by --force; bypasses audience.
• ↛ audience miss: user didn't match the audience predicate.
• ↛ exclusion loser (winner: <id>): matched, but a higher-priority experiment in the same exclusion_group won.

Exit codes

$dif conclude

Conclude an active experiment. Several writes in one transaction:

1. Update the frontmatter: status: active → concluded, set concluded: <today>.
2. Replace the ## Decision section body.
3. Move dif/experiments/active/<id>.md → dif/experiments/concluded/<YYYY-MM>-<id>.md.
4. Prepend one learning to dif/surfaces/<surface>.md under ## Learnings.

Edits are computed before writing; a later filesystem failure rolls back on a best-effort basis.

Flags

Example

$dif conclude checkout-cta-v2 --decision "Shipped variant_a. +2.1% on returning visitors."
→ moved dif/experiments/concluded/2026-05-checkout-cta-v2.md
→ drafted ## Decision block
→ appended to dif/surfaces/home.md
  "Shipped variant_a. +2.1% on returning visitors."

The first line of the decision becomes the surface log summary, prefixed with the conclusion date and experiment id. Multi-line decisions stay in the experiment file's ## Decision block; only the first line is duplicated to the surface.

Exit codes

invariantafter a successful conclude, dif validate and dif build still pass.

$dif scaffold-audiences

Add the starter audience resolver files to an existing project. Idempotent. Existing files are kept unless --force is supplied.

Creates dif/audiences/ if needed and writes locale.ts and device_type.ts. It never modifies dif/config.yaml; it prints the declaration snippet to add under audience_attributes yourself.

$dif scaffold-audiences
✓ wrote dif/audiences/locale.ts
✓ wrote dif/audiences/device_type.ts
→ add these to dif/config.yaml under audience_attributes:
    - { name: locale, type: string }
    - { name: device_type, type: enum, values: [mobile, tablet, desktop] }

Exit codes