/fallow-review

name: fallow-review
description: >-
  Review AI-generated or human-written code changes with fallow's
  graph-grounded review brief. Subtracts deterministic concerns (unused code,
  complexity, duplication, styling) from the loop, ranks what to look at by
  blast radius and risk, and surfaces the few consequential structural
  decisions (new public-API contracts, coupling/boundary crossings, new
  dependencies) as framed judgment questions anchored to verifiable signals.
  Drives a closed agent-contract loop: fetch the walkthrough guide, return a
  judgment, and have fallow post-validate it against the live graph
  (hallucinated or stale judgments are rejected). Use when asked to review a
  PR, review a branch, review a diff, do a code review, or check changed code
  before merge.
license: MIT

Fallow Review: graph-grounded code review

`fallow review` turns a changeset into a deterministic, graph-derived review brief and an agent-contract loop. It answers "where do I look, and what calls actually need human taste?" rather than "will CI block this?" (that is `fallow audit`, which gates). `review` always exits 0, so it is safe to run regardless of verdict.

The four jobs it does, in order:

• **subtract**: dead code, complexity, duplication, and styling for the changed files are reported and kept OUT of the judgment loop, so attention is not spent on what a deterministic check already owns.
• **focus**: changed-file units are ranked by a composite attention score (fan-in/out, risk zone, change shape) with a `review-here` / `not-prioritized` label and a full `deprioritized` escape-hatch list, so nothing is hidden.
• **structure**: the decision surface lifts the handful of consequential STRUCTURAL decisions out of the diff and frames each as a judgment question, capped to a working-memory-sized set, each anchored to a `signal_id` fallow emitted.
• **direct**: the walkthrough guide hands an agent a graph-derived digest, the review direction, a graph-snapshot pin, and the exact judgment schema to return.

When to use

• Reviewing a PR, branch, or diff (AI-generated or human-written) before merge.
• After an agent has done work and removed the fallow findings it could; this surfaces what is left for human/agent taste.
• Producing inline-reviewable judgments that can flow back to the agent that wrote the code.

When NOT to use

• Gating CI on a pass/fail verdict: use `fallow audit` (it exits non-zero on a fail verdict).
• Whole-project health, cleanup, or dead-code reports: use the `fallow` skill.

Quick human brief

# Auto-detect the base (merge-base against the upstream / remote default):
fallow review

# Pin the base, or scope to a precise diff:
fallow review --base origin/main
git diff --find-renames origin/main...HEAD | fallow review --base origin/main --diff-stdin

The human brief prints the orientation facts, the focus map, and the decision surface ("Decisions to make"). `--format json` emits the full structured envelope (`decisions`, `focus`, `deltas`, `impact_closure`, `partition`, `graph_facts`). `--max-decisions N` tunes the cap (clamped to a small band). `--show-deprioritized` expands what the focus map collapsed.

The decision surface

Each decision is a framed question anchored to a `signal_id` fallow deterministically derived from the graph (a delta key or a coordination-gap key). There are exactly three shippable categories:

• **coupling-boundary**: a new cross-zone dependency edge.
• **public-api-contract**: a new exported public-API surface, or a changed contract consumed by modules OUTSIDE this diff (a coordinate-or-confirm signal).
• **dependency**: a changed `package.json` that adds third-party entries or moves a declared entry across a major version (or a `0.x` minor). One batched decision per manifest per kind, weighted by the graph's in-repo importers of the affected packages: `blast` is the importer count, `internal_consumer_count` the importers outside the diff. Both counts are a union over the batched packages. An entry outside `dependencies` shows a `(dev)`, `(optional)`, or `(peer)` tag in the question. `digest.deltas` carries the keys as `dependency_added` (`<manifest>::<name>`) and `dependency_major_bumped` (`<manifest>::<name>@<from>-><to>`); both lists are always present, possibly empty. Minor and patch bumps and non-numeric ranges (workspace, file, git, tags) are never candidates. A `dependency` decision has no `suppress` action: it anchors on `package.json`, which cannot carry a comment, so never paste a `// fallow-ignore` line into a manifest. The `decision_surface` MCP tool surfaces the same dependency decisions as the CLI. Framing rule: cite the changelog question ("which documented change in `<from>` to `<to>` reaches these N importers?"); do not guess the behavior change.

A decision may carry `previous_signal_id` when its anchor file was renamed in the change: that is the `signal_id` the same decision would have had at the old path, so a review surface can re-attach a prior reviewer comment across a `git mv`.

Eliciting the broader trade-offs (taste ownership)

The decision surface above is the DETERMINISTIC slice: only the trade-offs fallow can prove from the graph (the three categories). Real architectural trade-offs are broader (abstraction level, error-handling strategy, data-model shape, eager-vs-lazy, state ownership, extensibility-vs-YAGNI, testability, trust boundaries), and none of those are graph-detectable. Surfacing them needs a model reading the diff, not a static pass.

Run the trade-off elicitation prompt in `references/tradeoff-elicitation.md` over the diff plus the guide. It applies TASTE OWNERSHIP: the model makes each choice legible and frames a genuinely open question; the human decides. The prompt carries the honesty contract (diff anchoring, the `observed` / `tradeoff` / `question` split, `deterministic: false` fencing, provenance, the top-five cap with honest abstention, no duplication of the d