sarif-parsing

# SARIF Parsing Best Practices

You are a SARIF parsing expert. Your role is to help users effectively read, analyze, and process SARIF files from static analysis tools.

## When to Use

Use this skill when:
- Reading or interpreting static analysis scan results in SARIF format
- Aggregating findings from multiple security tools
- Deduplicating or filtering security alerts
- Extracting specific vulnerabilities from SARIF files
- Integrating SARIF data into CI/CD pipelines
- Converting SARIF output to other formats

## When NOT to Use

Do NOT use this skill for:
- Running static analysis scans (use CodeQL or Semgrep skills instead)
- Writing CodeQL or Semgrep rules (use their respective skills)
- Analyzing source code directly (SARIF is for processing existing scan results)
- Triaging findings without SARIF input (use variant-analysis or audit skills)

## SARIF Structure Overview

SARIF 2.1.0 is the current OASIS standard. Every SARIF file has this hierarchical structure:

```
sarifLog
├── version: "2.1.0"
├── $schema: (optional, enables IDE validation)
└── runs[] (array of analysis runs)
    ├── tool
    │   ├── driver
    │   │   ├── name (required)
    │   │   ├── version
    │   │   └── rules[] (rule definitions)
    │   └── extensions[] (plugins)
    ├── results[] (findings)
    │   ├── ruleId
    │   ├── ruleIndex (index into tool.driver.rules[])
    │   ├── level (OPTIONAL, inherited from the rule when absent)
    │   ├── message.text
    │   ├── locations[]
    │   │   └── physicalLocation
    │   │       ├── artifactLocation.uri
    │   │       └── region (startLine, startColumn, etc.)
    │   ├── fingerprints{}
    │   └── partialFingerprints{}
    └── artifacts[] (scanned files metadata)
```

### Severity Is Not Always on the Result

`result.level` is optional. CodeQL omits it on every result and records severity on the
rule as `defaultConfiguration.level`, which the result inherits. Read `result.level`
directly and a CodeQL run scores as clean however many errors it found, which is how a
severity gate ends up exiting 0 on a failing repo.

Resolve severity in this order (SARIF 2.1.0 section 3.27.10):

1. `kind` other than `"fail"` (a pass/notApplicable record), so `"none"`
2. `result.level`, when present
3. the matched rule's `defaultConfiguration.level`, joining `ruleIndex` into
   `runs[].tool.driver.rules[]`, or matching `ruleId` against `rules[].id` when the tool
   omits `ruleIndex`
4. `"warning"`, the SARIF default

Every severity query in this skill starts from that resolution. In jq it is the
`LEVEL_FN` definition in [{baseDir}/resources/jq-queries.md]({baseDir}/resources/jq-queries.md);
in Python it is `resolve_level(result, run)` in
[{baseDir}/resources/sarif_helpers.py]({baseDir}/resources/sarif_helpers.py).

### Why Fingerprinting Matters

Without stable fingerprints, you can't track findings across runs:

- **Baseline comparison**: "Is this a new finding or did we see it before?"
- **Regression detection**: "Did this PR introduce new vulnerabilities?"
- **Suppression**: "Ignore this known false positive in future runs"

Tools report different paths (`/path/to/project/` vs `/github/workspace/`), so path-based matching fails. Fingerprints hash the *content* (code snippet, rule ID, relative location) to create stable identifiers regardless of environment.

## Tool Selection Guide

| Use Case | Tool | Install / run |
|----------|------|--------------|
| Quick CLI queries | jq | `brew install jq` / `apt install jq` |
| Python scripting (simple) | pysarif | `uv run --with pysarif python script.py` |
| Python scripting (advanced) | sarif-tools | `uv run --with sarif-tools python script.py` |
| .NET applications | SARIF SDK | NuGet package |
| JavaScript/Node.js | sarif-js | npm package |
| Go applications | garif | `go get github.com/chavacava/garif` |
| Validation | SARIF Validator | sarifweb.azurewebsites.net |

## Strategy 1: Quick Analysis with jq

For rapid exploration and one-off queries:

```bash
# Pretty print the file
jq '.' results.sarif

# Count total findings
jq '[.runs[].results[]] | length' results.sarif

# List all rule IDs triggered
jq '[.runs[].results[].ruleId] | unique' results.sarif

# Severity resolution, needed by every query below that filters on level.
# See resources/jq-queries.md for the annotated version.
LEVEL_FN='
  def rule($run):
    . as $r
    | ($run.tool.driver.rules // []) as $rules
    | (if ($r.ruleIndex | type) == "number" and $r.ruleIndex >= 0
       then $rules[$r.ruleIndex] else null end)
      // first($rules[] | select(.id == $r.ruleId))
      // null;
  def level($run):
    . as $r
    | if ($r.kind // "fail") != "fail" then "none"
      else ($r.level // rule($run).defaultConfiguration.level // "warning") end;
'

# Extract errors only
jq "$LEVEL_FN"'.runs[] as $run | $run.results[] | select(level($run) == "error")' results.sarif

# Get findings with file locations
jq '.runs[].results[] | {
  rule: .ruleId,
  message: .message.text,
  file: .locations[0].physicalLocation.artifactLocation.uri,
  line: .locations[0].physicalLocation.region.startLine
}' results.sarif

# Filter by severity and get count per rule
jq "$LEVEL_FN"'[.runs[] as $run | $run.results[] | select(level($run) == "error")] | group_by(.ruleId) | map({rule: .[0].ruleId, count: length})' results.sarif

# Extract findings for a specific file
jq --arg file "src/auth.py" '.runs[].results[] | select(.locations[].physicalLocation.artifactLocation.uri | contains($file))' results.sarif
```

## Strategy 2: Python with pysarif

For programmatic access with full object model:

```python
from pysarif import load_from_file, save_to_file

# Load SARIF file
sarif = load_from_file("results.sarif")

# Iterate through runs and results
for run in sarif.runs:
    tool_name = run.tool.driver.name
    print(f"Tool: {tool_name}")

    for result in run.results:
        # pysarif fills a missing result.level with "warning", so .level here is NOT the
        # rule-inherited severity: a