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02/08/2026 12:28 pm
TL;DR: Advanced rule power paired with a structured UI removes many YAML indentation and typing mistakes while preserving interoperability with advanced mode and supporting nested patterns and match inspection, according to Semgrep. For security teams, the shift matters because rule authoring quality often determines whether detections scale across code security and secrets workflows.
NHIMG editorial — based on content published by Semgrep: Structure mode makes rule writing less error-prone
By the numbers:
- 803/1920 = 41.8% of all rules in the semgrep-rules repository use features which are not expressible in simple mode.
- In the proprietary Semgrep rules repository, this number goes up to 65%.
Questions worth separating out
Q: How should security teams manage complex Semgrep rules without introducing syntax errors?
A: Use a structure-aware workflow for drafting, testing, and reviewing rules that contain nested logic or advanced operators.
Q: Why do advanced rule features matter for code security and secrets detection?
A: Advanced features allow authors to express logic that simple pattern lists cannot capture, including nested conditions, regex on metavariables, and taint-style analysis.
Q: What do security teams get wrong about rules-based identity detection?
A: They assume identity abuse will present a known bad indicator.
Practitioner guidance
- Separate rule intent from YAML mechanics Adopt structure-aware workflows for teams that write nested or high-variance Semgrep rules, especially where indentation errors have previously caused broken detections.
- Validate advanced rules before rollout Test rules in a controlled pipeline with representative code samples and deliberately malformed examples to confirm match behaviour, especially for patterns using metavariable-regex, inside, or nested any and all operators.
- Treat detection content as governed artefacts Assign owners, review cadence, and change history to custom rules the same way you would for security policies.
What's in the full article
Semgrep’s full post covers the editor mechanics and rule-writing workflow details this post intentionally leaves for the source:
- How structure mode maps advanced rule operators into a UI workflow without losing YAML export fidelity
- How match badges, drag and drop, and pattern disabling support rule debugging during authoring
- How simple mode limits rule expressiveness for nested patterns, metavariables, and taint logic
- How the editor distinguishes structural patterns from constraints during rule evaluation
👉 Read Semgrep’s explanation of structure mode for rule writing →
Semgrep structure mode: what it changes for rule writers?
Explore further
02/08/2026 1:26 pm
Structure-aware rule editing reduces detection debt. Security teams often treat rule authoring as a syntax problem, but the deeper issue is governance over detection intent. When rule format errors can silently disable content, organisations accumulate detection debt just as they do with unmanaged secrets or stale access policies. The relevant lesson for application security teams is that usability directly affects control reliability.
A question worth separating out:
Q: How do teams know whether custom detection rules are actually working?
A: They should test rules against representative code and expected failures, then inspect which sub-patterns are producing matches. If a rule matches only because of one fragment or never matches at all, the detection logic needs revision. Good governance means measuring rule behaviour, not just checking that the YAML file parses.
👉 Read our full editorial: Structure mode makes Semgrep rule writing less error-prone
