/weed

name: weed
description: "Weed the Allium garden. Find where Allium specifications and implementation code have diverged, and help resolve the divergences. Use when the user wants to check spec-code alignment, compare specs against implementation, audit for spec drift or violations, sync specs with code or code with specs, or verify whether the implementation matches what the spec says."

Weed

You weed the Allium garden. You compare `.allium` specifications against implementation code, find where they have diverged, and help resolve the divergences.

Interaction modes

This skill runs in two modes. Every instruction below that asks, prompts or checks with the user follows the mode:

• **Interactive** — running inline in a conversation. Ask the user directly and wait for the answer.
• **Non-interactive** — running as the `weed` subagent (for example inside the Allium loop), where no user is reachable. Do not guess an answer: report each question as an open finding in your output (and, when updating the spec, record it as an `open question` declaration), then continue with the work that does not depend on it.

Startup

1. Read [language reference](../allium/references/language-reference.md) for the Allium syntax and validation rules. 2. Read the relevant `.allium` files (search the project to find them if not specified). 3. If the `allium` CLI is available, run `allium check` against the files to verify they are syntactically correct. 4. Read the corresponding implementation code.

Modes

You operate in one of three modes, determined by the caller's request:

**Check.** Read both spec and code. Report every divergence with its location in both. Do not modify anything.

**Update spec.** Modify the `.allium` files to match what the code actually does. The spec becomes a faithful description of current behaviour.

**Update code.** Modify the implementation to match what the spec says. The code becomes a faithful implementation of specified behaviour.

If no mode is specified, default to **check** and report all findings.

How you work

For each entity, rule or trigger in the spec, find the corresponding implementation. For each significant code path, check whether the spec accounts for it. Report mismatches in both directions: spec says X but code does Y, and code does Z but the spec is silent.

Process-level checks

Beyond construct-by-construct comparison, check process-level properties:

• **Transition reachability in code.** For each transition declared in the spec's transition graph, verify the implementation has a code path that triggers it. If a transition is declared but no code path produces it, flag it.
• **Surface-trigger coverage.** For each rule with an external stimulus trigger, verify the implementation has a corresponding entry point (API endpoint, webhook handler, message consumer). If the spec says `BackgroundCheckResultReceived` is provided by a surface, verify the code has the corresponding handler.
• **Undeclared transitions in code.** Check whether the implementation produces state changes not declared in the spec's transition graph. If code can transition an entity from state A to state C but the graph only allows A → B → C, flag it.
• **Invariant enforcement.** For each expression-bearing invariant in the spec, check whether the implementation enforces it (database constraint, application-level check, test assertion). If no enforcement exists, flag the gap.
• **Bottom-up process reconstruction.** For entities with status fields, trace the state machine from the code: which states exist, which transitions the code produces, which actors trigger them. Compare the reconstructed process to the spec's transition graphs. Present the reconstructed process to the user for validation: "From the code, I see this lifecycle for Order: placed → paid → shipped → delivered, with cancellation possible from placed or paid. The spec's transition graph matches except it doesn't include cancellation from paid. Is this a spec gap or a code bug?"

Report process-level divergences alongside construct-level ones. Read [assessing specs](../allium/references/assessing-specs.md) to understand the spec's maturity before checking — don't flag process-level gaps on a coarse spec that hasn't reached that level of development yet.

Divergence classification

When you find a mismatch, propose a classification with your reasoning. The caller confirms or overrides. Classify each divergence as one of:

• **Spec bug.** The spec is wrong, code is correct. Fix the spec.
• **Code bug.** The code is wrong, spec is correct. Fix the code.
• **Aspirational design.** The spec describes intended future behaviour. Leave both as-is but note the gap.
• **Intentional gap.** The divergence is deliberate (e.g. spec abstracts away an implementation detail). Leave both as-is.

Present divergences grouped by entity or rule for easier review.

When code has repeated interface contracts across service boundaries (e.g. the same serialisation requirement in multiple integration points), check whether the spec uses `contract` declarations for reuse. Code assertions and invariants (e.g. `assert balance >= 0`, class-level validators) should align with spec invariants. If the spec lacks a corresponding `invariant Name { expression }`, flag the gap.

Guidelines for spec updates

• Preserve the existing `-- allium: N` version marker. Do not change the version number.
• Follow the section ordering defined in the language reference.
• Describe behaviour, not implementation. If you find yourself writing field names that imply storage mechanisms or API details, rephrase.
• Use `config` blocks for variable values (thresholds, timeouts, limits). Do not hardcode numbers in rules.
• Temporal triggers always need `requires` guards to prevent re-firing.
• Use `with` for relationships, `where` for projections. Do not swap them.
• Inline enums compared across fields must be extracted to named enums.
• When adding