review.default_reviewers config key scopes the no-flag /gsd-review fan-out

• Status: Proposed
• Date: 2026-05-13

We propose adding a review.default_reviewers key to .planning/config.json that scopes the no-flag default of /gsd-review to a user-chosen subset of detected CLI reviewers. Today the no-flag branch of workflows/review.md (line 52) invokes all available CLIs, which for multi-CLI users plus local model servers (ollama, lm-studio, llama.cpp) means probing up to ~10 backends per review, paying timeout costs on servers that aren't running and burning tokens on reviewers the user doesn't want for routine work (#3079). The only workaround today is patching workflows/review.md in place; that patch is wiped on every /gsd-update and requires /gsd-update --reapply to restore, with no machine-readable record of intent. The proposed key sits inside the existing review.* namespace (alongside review.models.<cli> and review.*_host), follows GSD's absent = enabled config philosophy, and is implementable as a one-line config read plus an intersection on the detected reviewer set.

Decision

• Add review.default_reviewers to the config.json schema as string[], validated against the existing CLI slug pattern ^[a-zA-Z0-9_-]+$ (the same pattern used for review.models.<cli> slugs).
• When the key is present, the no-flag branch of /gsd-review invokes only the reviewers listed in the key, intersected with the host's detect_clis result.
• When the key is absent, today's behavior is preserved: every detected reviewer runs. This matches the absent = enabled pattern documented in docs/CONFIGURATION.md.
• --all continues to mean "every detected reviewer" and ignores the config key.
• Individual reviewer flags (--gemini, --codex, --cursor, --claude, --opencode, …) continue to win over both config and --all.
• Resolution lives in the detect_clis step of workflows/review.md: detect first, then filter by review.default_reviewers only on the no-flag branch.
• Unknown slugs in the key emit a warning and are dropped; valid-but-undetected slugs emit an info-level note and are dropped; an all-undetected post-filter set emits an actionable error (see "Open questions" Q-1 for empty-array semantics).
• Slug comparison is lowercase-normalized on read. The schema pattern already accepts mixed case, so normalization is forgiving without making the pattern itself stricter.
• No new top-level config namespace, no new command, no new flag in v1.

Precedence (highest first):

1. Individual reviewer flags
2. --all
3. review.default_reviewers
4. No config, no flags → today's behavior (all detected)

Initial Scope

First slice should land the config plumbing and the no-flag branch behavior without expanding into adjacent reviewer-selection design:

1. Schema addition for review.default_reviewers in the config loader; validation as string[] with slug pattern; lowercase normalization; clear schema errors for non-array / non-string-element values.
2. Filter step inside workflows/review.md detect_clis no-flag branch:
   • intersect detected ∩ default_reviewers
   • emit a single-line "selection source" log identifying which path was taken (default config / --all / explicit flags / no config)
   • warn on unknown slugs; info on valid-but-undetected slugs; error if the post-filter selection is empty
3. Docs update: extend docs/CONFIGURATION.md with a review.* subsection documenting the key, allowed values, defaults, and override precedence; add the key to the schema block at the top of that file; update workflows/review.md to reference the key in the no-flag branch.
4. Tests: config parsing (valid / empty / malformed); detect_clis intersection; integration coverage of no-flag honors config, --all overrides, individual flags override, unknown slug warns, only-undetected slugs errors.
5. Release notes entry calling out the new key with the two-line config example.

It should not in the first pass:

• Add --no-default or any new CLI flag (track in "Open questions" Q-2 — likely equivalent to --all).
• Add per-phase or per-file-type reviewer profiles (review.profiles.*). The namespace is left open for this as a future ADR (see "Open questions" Q-3).
• Add reviewer "groups" or aliases (review.groups.cheap = [...]). Same — namespace deliberately left open.
• Auto-suggest defaults from usage history. Different design philosophy (silent behavior drift); explicitly out of scope.
• Extend /gsd-config --integrations to set the key interactively. Track as a fast follow (see "Open questions" Q-4).
• Change --all semantics or the individual flag set.

Migration Inventory

workflows/review.md

• detect_clis step, no-flag branch (current line 52: "No flags → include all available") — replace with: "No flags → if review.default_reviewers is set, intersect detected with the listed slugs; otherwise include all detected."
• Verbose / debug output path — emit one line identifying the selection source.

Config loader

• Add review.default_reviewers: string[] to the JSON schema for .planning/config.json. Pattern per element: ^[a-zA-Z0-9_-]+$. Slug list de-dup on read; lowercase-normalize on read.
• Surface schema errors at config load (file path + line number where the parser supports it), matching the existing handling for other malformed review.* keys.

docs/CONFIGURATION.md

• Add review.default_reviewers to the Full Schema code block at the top of the file as an optional array key under a "review": { ... } object.
• Add a new Reviewer Selection subsection (or extend the existing review.* section if one exists) covering: purpose, type, default, precedence vs. --all and individual flags, edge-case behavior (unknown slugs, undetected slugs, empty result).
• Cross-reference workflows/review.md for how the key is consumed at review time.

Tests expected to move with the seam

• New tests/review-default-reviewers-config.test.cjs:
  • valid ["gemini", "codex"] parses; lowercase normalization works
  • [] schema decision per Q-1 (proposed: parse-time error)
  • non-array → schema error
  • non-string element → schema error
  • element failing slug pattern → schema error
• New tests/review-default-reviewers-resolution.test.cjs:
  • no flags + key set, both slugs detected → exactly those reviewers invoked
  • no flags + key set, one slug undetected → info logged, remaining slug invoked
  • no flags + key set, all slugs undetected → actionable error, nothing invoked
  • no flags + key set, unknown slug present → warning logged, unknowns dropped, rest invoked
  • --all + key set → every detected reviewer invoked, key ignored
  • --gemini + key set to ["codex"] → only Gemini invoked
  • no flags + key absent → every detected reviewer invoked (back-compat)
• Extend existing /gsd-review integration tests to cover the new selection-source log line.

Schema doc cross-reference

• Update the schema example at the top of docs/CONFIGURATION.md to include "review": { "default_reviewers": ["gemini", "codex"] } so the key is discoverable from the canonical schema view.

Example config

{
  "review": {
    "default_reviewers": ["gemini", "codex"]
  }
}

With this set, /gsd-review (no flags) invokes only Gemini and Codex. /gsd-review --all invokes every detected reviewer. /gsd-review --cursor invokes only Cursor. Today's behavior is preserved by simply omitting the key.

Resolution pseudocode

detected = detect_clis()                  # unchanged
if any individual flag passed:
    selected = flags_to_set(flags) ∩ detected
elif --all:
    selected = detected
elif config.review.default_reviewers is set:
    valid    = filter(config.review.default_reviewers, is_known_slug)
    # warn on each invalid slug
    selected = valid ∩ detected
    # info on each valid-but-undetected slug
    if selected is empty:
        error with actionable message      # see Q-1
else:
    selected = detected                    # today's behavior
log_selection_source(selected, source)

Consequences

• Multi-CLI users can stop patching workflows/review.md; the patch class that /gsd-update wipes goes away for this case.
• Teams can commit .planning/config.json and share a default reviewer set across machines and contributors, without forking the workflow file.
• /gsd-review wall-clock time drops on machines where detection probes idle local model servers — the timeout cost on stopped daemons is no longer paid on every routine review.
• Schema surface grows by one optional key; doc maintenance and the test matrix grow by a small fixed amount.
• The review.* namespace stays internally consistent. Future review.profiles.* or review.groups.* can coexist with review.default_reviewers without renaming.
• Cross-runtime impact is minimal: the change operates on the detection layer in detect_clis, not on any per-runtime adapter. The existing resolve_model_ids: "omit" path used by non-Claude runtimes (Codex, OpenCode, Gemini CLI, Kilo) is unaffected.
• One additional surface area for bug reports — primarily edge interactions between the key and --all / individual flags, which the test plan covers.
• If telemetry is ever opt-in for .planning/config.json shape, adoption of this key becomes a useful signal for whether to invest in the richer profiles design (see Q-3).

Open questions

• Q-1. Should review.default_reviewers: [] be a schema error, or should it fall back to "all detected"? Proposal: schema error. Rationale: users who want "all detected" can simply omit the key (more readable); [] looks like a typo or programmatic mistake; surfacing the ambiguity is more helpful than silently swallowing it. Blocking — affects schema validation and tests.
• Q-2. Is a new --no-default flag warranted, or is it equivalent to --all for this use case? Proposal: drop unless a concrete difference surfaces during implementation. Non-blocking.
• Q-3. Do we want to commit now to leaving review.profiles.* open as a future namespace, or is that premature? Proposal: leave open; document the intent in docs/CONFIGURATION.md so the next contributor doesn't pick a conflicting key. Non-blocking.
• Q-4. Should /gsd-config --integrations learn the new key in this pass, or as a fast follow once the schema + resolution land? Proposal: fast follow. Non-blocking; depends on contributor bandwidth.
• Q-5. Should the verbose-mode "selection source" line ship in the first pass, or only behind --verbose? Proposal: behind --verbose. Non-blocking.
• Q-6. Slug normalization: lowercase-on-read (proposed) vs. exact-match enforcement at the schema layer. Proposal: normalize. Non-blocking; document either way.

References

• Feature issue: #3079
• Configuration reference: docs/CONFIGURATION.md — review.models.<cli>, review.*_host, and the absent = enabled pattern
• Workflow file owning the no-flag branch: workflows/review.md (line 52)
• Existing slug validation pattern: ^[a-zA-Z0-9_-]+$ (used for review.models.<cli> keys)
• Related PRD: 0011-review-default-reviewers-prd.md