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devin-rules-valid

Devin workspace rules must have valid activation frontmatter and fit its size limit
Severity error (auto)
Autofix -
Since v0.20.0
Repo Types devin
Category Devin

Why

Devin chooses when to load a workspace rule from the rule's YAML frontmatter. A malformed or unsupported trigger can leave an apparently authoritative file inactive. The activation data also depends on the mode: glob needs usable repository-relative patterns, while model_decision needs a description that lets the model route work to the rule.

Devin CLI reads rules below .devin/rules/ and the legacy .windsurf/rules/ spelling at the workspace root and in nested projects. Devin Desktop limits a workspace rule to 12,000 characters. Unknown frontmatter keys are accepted so a new upstream field does not make an otherwise valid rule fail.

Devin's documented bare glob scalar, such as globs: **/*.test.ts, parses even though strict YAML reserves a leading * for aliases. This exception applies only to the top-level globs value; unrelated malformed YAML is still reported. The scalar itself is an error: Devin Desktop may accept a single string, but the Devin CLI fails to load the rule ("expected a sequence"). A YAML list is the one form both hosts read. The CLI decodes globs and description even when the selected trigger does not use them: collection-valued descriptions and globs given as a single string or mapping still prevent loading. Nullable fields and scalar values accepted by Devin's YAML decoding remain accepted in unused fields.

Devin preserves scalar text in descriptions and glob-list items. For example, description: 42 participates in activation inference, and globs: [42, false] uses the patterns 42 and false. Collections remain invalid descriptions or glob-list items; a scalar globs field remains incompatible with the CLI. Devin ignores YAML merge keys (<<); declare activation fields explicitly.

Empty and comment-only frontmatter headers use the same activation defaults as an empty mapping. An explicit null document, malformed YAML, or a missing closing delimiter remains invalid.

Declare trigger, description, and globs only once per header. Devin rejects repeated known keys, including null-valued duplicates; skillsaw reports the repeated key's line. Duplicate unknown extension keys remain accepted.

Severity

Malformed YAML, an unsupported trigger, invalid activation data, and a rule over the configured character limit are errors because Devin may ignore the rule or be unable to activate it as intended.

trigger is optional; null also means unset. Without it Devin infers the mode: a non-empty globs list makes the rule glob-activated, a description makes it agent-decidable, and a rule with neither is manual (@rule). Absent, null and empty inferred globs allow description-based activation. An explicit trigger: glob still requires at least one pattern. A rule that never activates on its own is reported at info level.

Examples

Bad — the glob escapes the repository:

---
trigger: glob
globs:
  - ../shared/**
---

Use the shared API conventions.

Good — a model-selected rule with routing context:

---
trigger: model_decision
description: Apply when changing public API response shapes.
---

Preserve backward compatibility for existing response fields.

How to fix

  • Set trigger to always_on, manual, model_decision, agent, or glob, or omit it and let Devin infer the mode from globs or description.
  • For glob, provide a non-empty YAML list of repository-relative patterns. Remove absolute paths and .. path segments.
  • For model_decision, add a non-empty string description that explains when the rule applies.
  • Split or shorten a rule that exceeds max-characters (12,000 by default), or configure that option when a different host limit applies.

Configuration

rules:
  devin-rules-valid:
    enabled: auto  # true | false | auto
    severity: error
Parameter Description Default
max-characters Maximum characters in one Devin Desktop workspace rule 12000

Run skillsaw explain devin-rules-valid to see this documentation and the rule's effective configuration in your terminal.