Skylos

Open-source, local-first checks for dead code, security issues, secrets, quality regressions, and AI-code mistakes before merge.

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What Is Skylos?

Skylos is an open-source static analysis CLI for Python, TypeScript, JavaScript, Java, Go, Kotlin, PHP, Rust, Dart, C#, C++, Shell, and deployment config. It runs locally by default and can also be used as a CI/CD PR gate.

Use Skylos when you want one command to check a repo or pull request for:

• dead code and unused files
• security flaws and dangerous data flows
• secrets and dependency CVEs
• CI/CD and edge-device deployment misconfigurations
• quality regressions such as complexity, duplicate branches, and deep nesting
• common AI-generated code mistakes, including missing guards, fake helpers, invented package APIs, and impossible dependency versions
• LLM app risks such as unsafe tool use and missing output validation

Choose the Right Command

Each command answers a different question. The source scan requires PATH. Bracketed paths on verify, suite, defend, and clean default to the current directory. suite and defend require a directory; verify and clean also accept a file.

Question	Command	Input checked
What problems are in this source tree?	skylos PATH	Source files and project configuration; dead code by default, every main source analyzer with -a
Does this code contain AI-code mistakes?	skylos verify [PATH]	AI-defect checks over the selected file or tree, plus a separate Git HEAD behavior comparison for supported Python working changes
Will this exact local GPU build fit the machines we ship to?	skylos preflight [ARTIFACT]	A local built file or directory and .skylos/gpu-targets.yml; an OCI reference is identity-only and returns UNKNOWN in the CLI
What vulnerabilities are in this container image?	skylos image scan IMAGE@sha256:<digest> --platform os/arch	A remote registry image scanned by a separately installed Trivy; --fail-on turns findings into a gate
What does the combined repo suite report?	skylos suite [DIRECTORY]	Static analysis, technical debt, AI defense, and provenance; local findings are report-only by default
Does an agent implementation have deployment guardrails?	skylos defend [DIRECTORY]	Recognized Python and TypeScript/JavaScript LLM integrations; gating requires a threshold flag or policy
Which Python dead code can Skylos remove?	skylos clean [PATH] --dry-run	Python import/function cleanup candidates; --dry-run never writes

Run skylos --help for this chooser, skylos <command> --help for one command, and skylos commands for the command-family map.

The report commands have different gate and network behavior:

• image scan requires Trivy on trusted PATH and uses Trivy's remote image source, so registry network access and any required registry credentials must already be available. Without --fail-on, a completed scan exits 0 even when it reports vulnerabilities.
• suite runs in the local process and does not upload unless --upload is set, but its dependency scan can query OSV. Findings are report-only: the command exits 0 regardless of their count. Operational and output failures are nonzero; --upload can also fail for an upload error or Cloud quality gate.
• defend reports guardrail findings by default. It becomes a gate with --fail-on, --min-score, or gate settings in an explicit policy.
• clean without --dry-run or --apply is interactive and can write after the final confirmation. Its current codemods support Python imports and functions. An apply pass still exits 0 if an individual edit prints a failure, so review the completion output.

Start In 60 Seconds

pip install skylos
skylos .

The default scan focuses on dead code. Run every main source analyzer, including security, secrets, quality, dependency, and AI-defect checks, with -a:

skylos . -a

Run only evidence-backed AI defect checks with:

skylos . --ai-defects

Verify a repository, file, or range before an agent hands it to review:

skylos verify . --file src/app.py --range 40:75 --project-context

For a directory such as ., the AI-defect scan covers the selected tree. The separate behavior result models supported Python working-tree changes against Git HEAD; it is not the scope selector for the AI-defect scan. Dependency hallucination checks are enabled for path targets and can query package registries; use --no-dependency-hallucinations to disable those lookups. Interactive terminals get a human report. Redirected stdout and -o produce the versioned JSON result.

skylos verify schema version 2 returns pass, fail, or incomplete. incomplete means a requested proof could not be established, such as a third-party TS/JS import, computed namespace member, unsupported language-local API check, or parser surface that Skylos could not prove; it exits 2 unless --no-fail is set. The coverage object lists detected languages, expected checks, language support, missing checks, completed/skipped checks, checked references, and deterministic skip reasons.

Deterministic local/workspace API verification currently covers Python, TypeScript/JavaScript, Go, and Java without executing target code. PHP, Rust, Dart, C#, Kotlin, and Shell retain their existing static-analysis coverage, but their local API proof is reported as unsupported and therefore incomplete. See AI Code Verification Coverage.

Create a local AI hallucination contract for repo-specific generated-code truth. skylos verify auto-discovers .skylos/ai-contract.yml:

skylos contract init
skylos contract inspect
skylos verify .

Test a running agent against deterministic response and tool-use scenarios:

skylos agent init
skylos agent test --allow-contract-endpoint

Create a project config with thresholds, ignores, template hooks, and vibe dictionary extensions:

skylos init

Create a starter local rule pack:

skylos rules init
skylos rules validate .skylos/rules/local.yml
skylos rules list --json
skylos rules list cross --json
skylos rules list --packs --json
skylos cache stats

Generate a GitHub Actions PR gate:

skylos cicd init
git add .github/workflows/skylos.yml
git commit -m "Add Skylos CI gate"
git push

Need more commands? Read the CLI Reference.

Check an Exact GPU Release Artifact

skylos preflight checks the built artifact itself against the repository's declared GPU fleet. This is separate from the SKY-GPU* source scan, which checks Dockerfiles, CUDA build settings, and TensorRT packaging intent before the artifact exists.

Declare every machine that receives the same release:

# .skylos/gpu-targets.yml
version: 1
targets:
  - name: inference-t4
    vendor: nvidia
    driver: "535.104.05"
    compute_capability: "7.5"
    platform: "linux/amd64"

The canonical filename is .skylos/gpu-targets.yml; the same schema is also accepted as .skylos/gpu-targets.yaml.

Then inspect a local build. Skylos uses a trusted system cuobjdump, takes a private snapshot, and never loads or executes the artifact:

skylos preflight build/app

To make the command argument-free in CI, bind it to a project-relative artifact with a strict release receipt:

{"version": 1, "artifact": "build/app"}

Save that file as .skylos/release.json, then run skylos preflight. For requests that reach report generation, terminal output is concise and redirected output is schema-versioned JSON. Argument or adapter errors can be plain text and exit 2.

Status	Exit	Meaning
PASS	0	Every declared target is compatible within the stated static evidence scope, and the exact artifact identity is verified
FAIL	1	Artifact evidence proves at least one declared target incompatible
UNKNOWN	2	Required evidence is missing, ambiguous, unsupported, or incomplete; it never silently becomes a pass

cuobjdump can report several code-object groups, identified by the producer label in its selected executable fatbin. Skylos requires a compatible route for every reported group. A PTX-only route stays UNKNOWN because static inspection cannot prove that the deployment driver will JIT it successfully. The overall result is FAIL if any target or required check fails; otherwise it is UNKNOWN if any result is unknown, and PASS only when all results pass.

Version 1 proves the local artifact identity, Linux ELF platform, selected executable-fatbin architecture routes, a static packaged $ORIGIN CUDA runtime route, and documented CUDA driver-family compatibility. It does not prove runtime execution, workload correctness, memory demand, performance, nonselected or relocatable fatbins, or per-kernel symbol parity. Windows PE runtime import proof is not implemented. Digest-pinned OCI references are accepted as identities but are never pulled or started, so the CLI always reports UNKNOWN for them; trusted callers can supply digest-bound inspection facts through skylos.preflight.run_preflight(...).

Common Workflows

Goal	Command	What You Get	More Detail
First dead-code scan	skylos .	Finds unused functions, classes, imports, files, and framework entrypoint mistakes	Dead code docs
Deterministic cleanup preview	skylos clean . --dry-run --types import,function --confidence 80	Shows planned Python import/function removals without writing; add --apply to edit files	Dead code docs
Security and quality audit	skylos . -a	Adds dangerous flow, secrets, dependency, config, quality, and AI-defect checks	Security docs
Combined repo report	skylos suite .	Reports static findings, technical debt, AI defense, and provenance; SCA can query OSV, and findings alone exit 0	CLI Reference
Optional Python linting	pip install "skylos[lint]" && skylos lint .	Runs Ruff with its native configuration, output, fixes, and exit codes through the Skylos CLI	Python linting
PR gate	skylos cicd init	Generates a GitHub Actions workflow with annotations and failure thresholds	CI/CD guide
GitLab merge request report	skylos . --format gitlab -o gl-code-quality-report.json	Exports a native Code Quality report for GitLab CI artifacts	GitLab Code Quality
Offline dependency SBOM	skylos sbom . -o sbom.cdx.json	Lists supported recorded dependencies as CycloneDX 1.6 JSON without network requests	Dependency scanning
Container-image scan	skylos image scan IMAGE@sha256:<digest> --platform linux/amd64 --fail-on high	Uses separately installed Trivy, registry network/auth, and an explicit severity gate for a pinned remote image	Container-image scanning
Built GPU artifact preflight	skylos preflight build/app	Verifies the exact local artifact identity, selected CUDA architectures, packaged runtime route, and declared fleet compatibility; returns PASS, FAIL, or UNKNOWN	Release reliability
Container-image report import	skylos ingest trivy --input trivy.json --sarif image.sarif	Converts an existing Trivy image vulnerability report to Skylos JSON/SARIF; optional digest-bound severity check	Container-image scanning
Readable terminal report	skylos . --format pretty	Groups findings by file with severity badges, snippets, and copyable file:line locations	CLI output modes
Single-rule review	skylos . --select SKY-L012 --format concise	Enables the matching analyzer family and reports only that exact rule with its full message	CLI output modes
Selectable terminal triage	skylos . --tui	Opens a keyboard-driven category list, finding list, and detail pane	CLI output modes
IDE/test-script output	skylos --format concise src/test.py	Prints untruncated file:line RULE_ID message findings and exits non-zero when findings exist	CLI Reference
In-loop AI-code verification	skylos verify . --file src/app.py --range 40:75	Reports a narrow set of hallucinated helpers, unfinished code, stale references, disabled controls, and API/dependency hallucinations; JSON is used for redirected or -o output	AI features
AI hallucination contracts	skylos contract init && skylos verify .	Auto-discovers .skylos/ai-contract.yml and verifies generated code against repo-specific symbols, dependencies, APIs, route guards, and test requirements	AI Hallucination Contracts
Changed-lines review	skylos . -a --diff origin/main	Keeps findings focused on active work instead of legacy debt	Quality gate docs
Incumbent scanner comparison	skylos compare . --against incumbent.sarif [--upload]	Runs Skylos beside the current scanner and produces a revision-aware scorecard: active overlap, raw unique findings by category, and eligible findings inside evidence-backed unused symbols—without replacing the current gate. --upload preserves a project-bound Cloud receipt.	Scanner comparison
Kubernetes exposure proof	skylos . --select SKY-DEP001,SKY-DEP002,SKY-DEP003 --format concise	Checks an explicitly external, explicitly plain-HTTP Ingress chain inside one rendered multi-document bundle; route checks compare exact framework wiring with the workload's declared source file and required guards	Deployment exposure rules
GPU source/build intent gate	skylos . --select SKY-GPU000,SKY-GPU001,SKY-GPU002,SKY-GPU003 --gate --format concise	Checks declared CUDA image, architecture, driver, and TensorRT packaging intent before the artifact is built	GPU target contract
Runtime-assisted dead-code check	skylos . --trace	Uses runtime traces to reduce dynamic-code false positives	Smart tracing
Local rule pack	skylos rules init	Scaffolds YAML rules for project-specific security and quality checks	Custom rules
Security agent quick scan	skylos agent security-quick .	One-shot LLM security audit; compatibility alias for skylos agent scan . --security	AI features
Security agent deep scan	skylos agent security-deep .	Three-stage security workflow with threat-model context, static threat traces, discovery/validation, and remediation handoff	AI features
AI-assisted review	skylos agent scan .	Static analysis plus optional LLM review and fix suggestions	AI features
Agent harness replay	skylos agent replay .skylos/runs/<run-id>	Validates and summarizes saved agent verification phases, tool calls, decisions, and budgets	Agent harness artifacts
Runtime agent behavior test	skylos agent init && skylos agent test --allow-contract-endpoint	Checks final responses, tool selection, explicit refusals, and source IDs against a versioned contract	Agent Behavior Testing
Verification-backed remediation	skylos agent remediate .	Scans and fixes supported findings, then re-scans them and records proof-test metadata when available	AI features
MCP agent verification	verify_change MCP tool	Lets Claude, Cursor, and other MCP clients verify an edited file/range with the same schema as skylos verify	MCP server
LLM integration inventory	skylos discover .	Maps recognized LLM calls, agent tools, prompt sites, and input sources in Python and TypeScript/JavaScript	Agent verification
Pre-deployment agent verification	skylos defend . --format md -o evidence.md	Verifies agent guardrails, scores OWASP LLM/Agentic coverage, and emits an attested evidence report	Agent verification
Agent verification CI gate	skylos defend . --fail-on critical	Blocks deploys with unguarded LLM integrations; SARIF for code scanning via --format sarif	Agent verification
MCP agent pre-flight	verify_agent MCP tool	Lets coding agents statically verify the agents they build — scores, failed checks, attestation digest	MCP server
Technical debt triage	skylos debt .	Ranks hotspots and debt trends	Technical debt

What Skylos Catches

Category	Examples	Why It Matters
Dead code	unused functions, classes, imports, package entrypoints, route handlers	reduces maintenance cost without breaking dynamic frameworks
Security flaws	SQL injection, XSS, SSRF, path traversal, command injection, unsafe deserialization	catches exploitable flows before code reaches main
Secrets	API keys, tokens, private credentials, high-entropy strings	prevents credentials from leaking through commits and PRs
CI/CD workflows	GitHub Actions and GitLab CI dangerous triggers, unpinned actions/includes, broad tokens, OIDC misuse, cache poisoning, mutable images	reduces CI/CD supply-chain risk before release jobs run
Edge deployment config	Docker Compose privileged device access, host networking, systemd root services, broad capabilities, missing sandboxing	catches repo-controlled settings that turn app bugs into device compromise
Kubernetes deployment exposure	Explicitly external Ingress paths reaching a sensitive FastAPI/Flask route without its deployment-required guard, Flask --debug, or an application server using --reload	reports only when the resources are in one rendered bundle and every deployment edge resolves unambiguously
GPU release compatibility	source/build contract mismatches plus built-artifact identity, selected CUDA architecture, packaged runtime, and fleet checks	catches declared intent errors early and verifies the resulting local artifact before release
Quality regressions	complexity, deep nesting, duplicate branches, long functions, inconsistent returns	keeps AI-assisted refactors from adding brittle code
AI code mistakes	phantom security calls, missing decorators, unfinished stubs, disabled controls, real packages called with invented APIs, impossible npm/Go versions	catches common hallucinated or incomplete code paths before they reach review
LLM app risks	unsafe tool use, prompt injection exposure, missing output validation, missing rate limits	helps teams ship AI features with guardrails

See the full Rules Reference.

Verify AI Agents Before They Ship

Runtime guardrails are the WAF; Skylos is the SAST. skylos discover scans Python and TypeScript/JavaScript for recognized LLM integrations (provider SDKs, agent frameworks including the OpenAI Agents SDK, Claude Agent SDK, and Google ADK, MCP servers and their tools, direct HTTP calls to LLM APIs or OpenAI-compatible gateways, plus agent tools, prompt sites, and input sources). skylos defend checks the guardrails around those detected integrations deterministically, in the local process, with no model in the loop. It emits evidence by default and becomes a CI gate only when a threshold flag or policy supplies gate criteria.

skylos discover .                               # inventory LLM integrations and agent tools
skylos defend .                                 # score guardrails (13 weighted checks)
skylos defend . --format md -o evidence.md      # auditor evidence report + attestation
skylos defend . --format sarif -o defend.sarif  # GitHub code scanning upload
skylos defend . --fail-on critical              # CI gate: exit 1 on critical gaps
skylos defend . --owasp-framework agentic       # report against OWASP Agentic ASI Top 10

These commands do not inspect integrations in other languages. If discovery finds no supported integration, defend returns an empty inventory; do not treat the resulting score by itself as proof that an unsupported or unrecognized agent implementation has guardrails.

Per integration it verifies: dangerous output sinks (eval/exec/subprocess), agent tool scope and typed schemas, prompt-injection exposure (delimiters, untrusted input paths, RAG context isolation), output validation, PII filtering, and model pinning — plus ops checks (logging, cost controls, rate limiting) scored separately so they never inflate the security score.

• OWASP mapping: LLM Top 10 (2024/2025) and Agentic ASI Top 10 (2026).
• Evidence report (--format md): integration inventory, per-check results, OWASP coverage, regulatory framework evidence (EU AI Act, NIST AI RMF, ISO/IEC 42001 — "evidence toward" mappings, never compliance claims), and a remediation appendix.
• Attestation: JSON/md/SARIF reports carry a reproducible SHA-256 digest over file contents, policy, plugin set, integration inventory, scores, and full check evidence — re-run on the same tree with the same flags and Skylos version, and the digest must match.
• CI-native: skylos cicd init --defend generates the workflow step, the skylos-defend pre-commit hook gates locally, and $GITHUB_STEP_SUMMARY gets a score summary automatically in Actions.
• Policy as code: skylos-defend.yaml pins gate thresholds and severity overrides (--policy).
• Agent-native: the verify_agent MCP tool lets coding agents verify the agents they build — deterministic verification, not AI checking AI.

Static pre-deployment verification complements runtime controls (gateways, policy engines, human approval flows); it does not replace them. Full guide: docs/agent-verification.md.

Test Running Agent Behavior

Skylos separates generated-code truth, static agent guardrails, and observed runtime behavior:

Command	Verification question
skylos verify	Did the agent generate valid, non-hallucinated code?
skylos defend	Does the agent implementation contain the required guardrails?
skylos agent test	Did the running agent behave according to its contract?

Create .skylos/agent-test.yml, then test a live OpenAI-compatible endpoint:

skylos agent init
skylos agent test --allow-contract-endpoint

Or evaluate captured evidence without a network call:

skylos agent test --observations agent-observations.json
skylos agent test --observations agent-observations.json \
  --format json --output agent-results.json

Version 1 deterministically checks exact response substrings, required, allowed, and forbidden tool calls, tool arguments and sequence, maximum call count, explicit refusals, and explicit source IDs. Missing typed evidence is incomplete, never pass; exit codes are 0 pass, 1 violation, and 2 incomplete/invalid. Tool selection and final-answer source-ID checks are separate one-turn scenarios: Skylos records local replayable evidence but never executes tools returned by the target agent. Offline observations are marked as unverified fixtures rather than runtime proof.

For an authenticated remote endpoint, keep the destination and secret choice in the trusted CLI invocation:

skylos agent test --endpoint https://agent.example.com/v1/chat/completions \
  --allow-remote --auth-env MY_AGENT_API_KEY

Full guide: docs/agent-behavior-testing.md.

How Skylos Fits

Skylos is not a replacement for every specialized scanner. It is a local-first repo and PR checker that puts several common review checks behind one CLI.

• Framework-aware dead code detection: FastAPI, Django, Flask, pytest, SQLAlchemy, Next.js, React, package entrypoints, and common plugin patterns.
• PR-focused output: diff scanning, CI thresholds, GitHub annotations, and baselines for existing findings.
• Local-first operation: core analysis executes locally and does not upload source or call an LLM. Dependency/CVE checks can query OSV or package registries, and direct container scanning contacts a registry through Trivy.
• AI-assisted change review: checks for removed validation, auth, logging, CSRF, rate limiting, timeouts, real-package API hallucinations, and other guardrails in generated or edited code.
• Agent-loop verification: skylos verify and MCP verify_change use a versioned result schema for AI-code trust findings, so coding agents can self-correct before a human sees the change. The CLI renders a human report on a terminal and JSON when redirected or written with -o.
• Evidence-backed AI defects: --ai-defects and full scans put strict AI-code failure checks under ai_defects, including phantom references, fake package APIs, nonexistent packages, impossible dependency versions, and weakened test assertions. The category/tag is ai_defect; several rules intentionally keep historical SKY-L or SKY-D IDs for suppression and baseline compatibility, while new AI-defect-only checks use SKY-A.
• Verification-backed remediation: security fixes are checked by re-running analysis, and supported findings can include targeted regression-test proof metadata.
• Project-specific rules: add local YAML rules and extend prompt, credential, sensitive-file, and timeout dictionaries from config.
• One command surface: dead code, security, secrets, dependency, quality, technical debt, agent review, and pre-deployment agent verification commands share the same CLI.

Agent Harness Artifacts

skylos agent verify . and skylos agent test record replayable artifacts under .skylos/runs/<run-id> and print the run directory in table output. JSON output includes the same harness summary under the harness key.

Use skylos agent replay .skylos/runs/<run-id> to validate and inspect a saved run without making LLM calls. Add --format json when another agent or CI job needs machine-readable status. A valid replay exits 0; an invalid or corrupt artifact set exits 1 with issue codes. Replay output includes schema_version so CI and agents can detect artifact-contract changes. Replay checks internal consistency and corruption; artifacts are not signed and are not proof against an actor that can rewrite the entire run directory.

Each run directory contains:

• events.jsonl: chronological run, phase, and tool-call events.
• state.json: full observable state, including phases, tool calls, decisions, and budget usage.
• summary.json: compact status, counts, budget, and artifact paths.
• behavior-results.json: normalized runtime assertions, provenance, coverage, and a digest-bound evidence report for skylos agent test runs.

The current harness state is observable and replay-validated. It is not yet a resume mechanism for continuing interrupted verification runs.

Install Options

# Core static analysis
pip install skylos

# LLM-powered agent workflows
pip install "skylos[llm]"

# Ruff Python linting through `skylos lint`
pip install "skylos[lint]"

# All published optional extras
pip install "skylos[all]"

Container image:

docker pull ghcr.io/duriantaco/skylos:latest
docker run --rm -v "$PWD":/work -w /work ghcr.io/duriantaco/skylos:latest . --json --no-provenance

The unqualified image uses Python 3.14. Runtime-specific tags are also published for Python 3.11 through 3.14, so container scans can match a local or CI parser exactly:

docker run --rm -v "$PWD":/work -w /work ghcr.io/duriantaco/skylos:latest-python3.13 . --json --no-provenance

If a Python file cannot be parsed, Skylos reports analysis_errors, omits the grade, and exits with code 2 instead of treating the skipped file as clean.

See Installation for source installs, container usage, and optional dependencies.

Configure Templates And Vibe Checks

Run skylos init to add these sections to pyproject.toml:

[tool.skylos]
exclude = ["node_modules", "dist"]

[tool.skylos.templates]
# security = ".skylos/templates/security.md"
# quality = ".skylos/templates/quality.md"
# security_audit = ".skylos/templates/security_audit.md"
# review = ".skylos/templates/review.md"

[tool.skylos.vibe]
extra_phantom_names = ["verify_enterprise_auth"]
extra_phantom_decorators = ["tenant_admin_required"]
extra_credential_names = ["tenant_signing_secret"]
extra_network_timeout_calls = ["vendor_sdk.fetch"]

[tool.skylos.dead_code]
entrypoints = []

[[tool.skylos.dead_code.entrypoints]]
type = "method"
name = ["create", "pre_hook", "post_hook"]
parent = { name = "Main", base_classes = ["Application"] }
path = "src/**"
reason = "project framework lifecycle hook"

[tool.skylos.contribution]
collect_local_signals = false
contribute_public_corpus = false
structural_signatures_only = true
include_source = false

Template files extend Skylos' built-in prompts; they do not replace the JSON-only output contract or untrusted-code safety rules. Vibe dictionary extensions let teams teach Skylos about local fake-auth helpers, project credential names, sensitive files, and network calls that must set timeouts. Dead-code entrypoints let teams mark proprietary framework classes, lifecycle methods, and decorator-registered functions as live using precise rules for type, name, path, decorators, base classes, and parent classes. Rules must include a symbol selector such as name, decorators, base_classes, or parent; path and module only narrow the match. Contribution signals are off by default; when enabled, Skylos records local structural accept/dismiss/learn events under .skylos/contribution/ without raw source.

By default Skylos discovers [tool.skylos] in pyproject.toml by walking up from the scan path. To use a dedicated TOML config, pass --config-file PATH or set SKYLOS_CONFIG_FILE; standalone files may use either [tool.skylos] or top-level [skylos]. Synced Skylos Cloud policy keeps its protected precedence over repository-controlled config. The top-level [tool.skylos].exclude list applies to the main scan and commands such as skylos debt and skylos clean; pass --exclude for command-local additions or --include-folder to override an excluded folder.

Language Support

Language	Dead Code	Security	Quality	Local API Proof (verify)	Notes
Python	Yes	Yes	Yes	Supported	strongest coverage; framework-aware static analysis and optional tracing
TypeScript / JavaScript	Yes	Yes	Yes	Supported	Tree-sitter parsing, package graph reachability, framework conventions
Java	Yes	Yes	Yes	Supported	Tree-sitter parsing, structured security-flow analysis, conservative static-member proof
Go	Yes	Partial	Partial	Supported	native engine status remains separate from deterministic workspace API proof
PHP	Yes	Yes	Partial	Unsupported	PHP parser coverage plus taint-style security sinks and sources
Rust	Yes	Yes	Partial	Unsupported	Rust parser coverage plus security sink/source checks
Dart	Yes	Yes	Partial	Unsupported	Dart parser coverage plus selected security sinks and sources
C#	Yes	Yes	Partial	Unsupported	C# symbol coverage plus selected ASP.NET, process, SQL, HTTP, and file sinks
C++	Partial	No	No	Unsupported	conservative unused file-local functions in .cpp, .cc, .cxx; C++ headers are parsed for references
Kotlin	Yes	Partial	Partial	Unsupported	Kotlin symbol extraction with conservative static-analysis coverage
Shell	No	Yes	Partial	Unsupported	shell-script security checks for command injection, SSRF, and path traversal

Java security analysis follows directly implemented request-data helpers in same-package files or source files identified by exact imports or fully qualified names under a verified local source root. Helper reads are bounded and reject symlinks; no Java code or build scripts are executed. This is not full classpath or recursive helper analysis. Unknown helpers are not assumed to be request sources or sanitizers.

C++ analysis covers .cpp, .cc, .cxx, .hpp, .hh, and .hxx. The first release reports only apparently unused file-local free functions. Without a build configuration, it cannot fully resolve templates, overloads, macros, or external usage; these findings are a conservative heuristic, not a proof of C++ deadness. Ambiguous .h files and C files are not analyzed as C++.

Java weak-hash checks also follow local algorithm variables and values loaded through java.util.Properties from literal classloader resources. Resource lookup stays within the matching src/main/resources or src/test/resources directory. Missing resources, unsupported loaders/layouts, conflicting branch values, and unresolved mutations remain unknown. Properties are used only as crypto evidence, never to prove a security guard or choose a safe branch. This does not resolve arbitrary runtime classpaths, JAR resources, or environment overrides.

TypeScript and JavaScript dead code analysis recognizes package.json entry fields, including bin. For targets under dist/ or out/, it checks the matching src/ location first, then the package root, before the declared output. This also covers dist/bin/palee.js mapping to bin/palee.ts and dist/src/index.js mapping to src/index.ts. If both source locations exist, the src/ mapping keeps priority; unrelated files are not treated as entries.

For ESM build scripts invoked by package scripts, Skylos also follows top-level esbuild calls using unchanged constants, spreads, templates, Node path helpers, and simple literal-array maps. Build scripts are never executed. Nested build calls and filesystem-generated entry lists remain unsupported and may still produce unused-file findings.

VitePress configs at .vitepress/config.* and .vitepress/config/index.* are recognised as development entrypoints for .js, .ts, .mjs and .mts. Other files in .vitepress still need a reference or another entrypoint rule. Existing directory conventions such as scripts/ work with native Windows separators too; this does not add general discovery of commands in CI workflows.

Vue single file components (.vue) are skipped by source analysis, including when passed explicitly. Skylos does not yet parse their <script> or <script setup> blocks; separate JavaScript, TypeScript and backend source files are still analyzed. Existing browser script and event references in templates are unaffected.

Go dead-code and security checks require the native skylos-go engine. If Skylos discovers Go files but cannot run that engine, the report is marked incomplete, no grade or clean result is produced, and the CLI exits with status 2. Run skylos doctor to verify engine availability and configure SKYLOS_GO_BIN when using a separately built engine. The official GitHub Action builds the matching native engine automatically.

See Rules Reference for rule families and scanner scope.

Config And Deployment Support

Surface	Files	Security Scope
GitHub Actions	.github/workflows/*.yml, .github/workflows/*.yaml, action.yml, action.yaml	dangerous triggers, token permissions, unpinned actions, template injection, secrets, OIDC, cache, and artifact policy
GitLab CI	.gitlab-ci.yml	mutable images, unpinned includes, literal secrets, untrusted eval, Docker-in-Docker, OIDC, cache, timeout, and runner-tag policy
Dockerfile	Dockerfile, Dockerfile.*, *.dockerfile	dangerous RUN commands, remote ADD without checksum, and literal build ARG / ENV secrets
Edge Docker Compose	compose*.yml, compose*.yaml, docker-compose*.yml, docker-compose*.yaml	privileged containers, broad host device/control mounts, GPU/device runtime, and host networking
Edge systemd	*.service	root edge services, mutable ExecStart paths, missing sandboxing, broad capabilities, and broad device access
Rendered Kubernetes exposure	one multi-document *.yml or *.yaml bundle plus a contracted Python source file	opt-in proof from an Ingress annotated skylos.dev/network-scope: external (or public) and skylos.dev/backend-protocol: http through its Service and workload; SKY-DEP001 checks direct top-level FastAPI/Flask routes against skylos.dev/source-file and skylos.dev/required-guards, SKY-DEP002 catches an effective Flask debugger, and SKY-DEP003 catches effective reload mode
GPU release contract	.skylos/gpu-targets.yml, Dockerfiles, CMake/CUDA build files, TensorRT source	static target-fleet checks for driver, compute-architecture, and serialized-engine compatibility; no hardware probing

Benchmark Snapshot

Skylos has checked-in regression benchmarks for dead code, security, quality, and agent review. These are strict regression gates, not broad proof that any tool is universally state of the art.

Suite	Current Skylos Result	Baseline
Dead code regression	16 cases, TP=36 FP=0 FN=0 TN=59, score 100.0	Ruff score 62.67; Vulture not installed in latest local rerun
Security regression	56 cases, TP=35 FP=0 FN=0 TN=23, score 100.0	Bandit score 47.14 on Python-applicable cases
Quality regression	13 cases, score 100.0	regression gate only
Agent review	25 cases, score 100.0	regression gate only
AI-code defect regression	curated verifier cases for hallucinated references, package APIs, and dependency versions	run python scripts/ai_code_defect_benchmark.py

Frozen golden-v0.2 highlights:

Frozen Suite	Skylos Result	Caveat
Dead code seeded dev	overall score 96.28; TS/JS/Go/Java score 100.0; Python score 93.33	Python residuals are label-review items
Security seeded dev	overall score 96.52; full recall with one Python urljoin false positive	label should be reviewed
OWASP Java security dev	TP=120 FP=0 FN=0 TN=120, score 100.0	240-case development subset, not general Java coverage; direct static analysis plus focused CLI checks
Quality seeded dev	TP=1 FP=0 FN=0 TN=1, score 100.0	one seeded case only

For methodology, commands, competitor rows, and caveats, see BENCHMARK.md.

Real-project regression testing

liveness_primer, created and maintained by Matthew Digman, is Skylos's official real-project regression testing tool. On every PR, it compares the base and proposed merge result against the same pinned Python projects and reports which findings were added, removed, or changed.

Read the Analyzer Blast Radius check for the comparison and downloadable reports. These results complement the labeled benchmarks above; a change in finding counts alone does not establish accuracy. See the liveness_primer guide for scope, review steps, and reproduction commands.

Project Evidence

Skylos-assisted dead-code cleanup PRs have been merged in Black, NetworkX, Optuna, mitmproxy, pypdf, beets, and Flagsmith. These are accepted cleanup PRs, not project endorsements. See Real-World Results.

A local Astronomer scan on April 26, 2026 computed 420 stargazers and returned overall trust: A. StarGuard also reported low fake-star risk.

Integrations

Integration	Link	Purpose
GitHub Action	GitHub Action	Repository PR gates or optional digest-pinned container-image gates
GitLab Code Quality	GitLab setup	merge request report artifacts; no comment-posting bot or API token
VS Code extension	VS Code extension	in-editor findings and AI-assisted fixes
MCP server	MCP setup	expose Skylos scans to AI agents and coding assistants
Ruff	Python linting	optional Python linting through skylos lint
Docker image	Installation	run Skylos without a local Python install
Skylos Cloud	Cloud workflow	optional upload and dashboard workflows

Generate a GitHub Actions workflow from the CLI:

skylos cicd init --upload
skylos cicd init --upload --scan-path apps/api

The generated workflow reviews changed lines on pull requests and uploads full scans on pushes using GitHub OIDC. It supports monorepo subprojects through --scan-path.

To scan a built image with the composite Action, install a pinned Trivy version in the caller's job and set image to a trusted repository@sha256:<digest> build output plus image-platform. This runs an image-only scan; mode: gate uses image-fail-on (default high), while mode: scan only reports findings. See container-image scanning.

Documentation Map

Need	Read This
Install options, source install, and Docker	Installation
First scan and core workflows	Quick Start
CLI commands, flags, and examples	CLI Reference
CLI output modes, pretty reports, and TUI controls	CLI Output Modes
Optional Ruff linting through the Skylos CLI	Python Linting
CI setup, PR gates, annotations, and branch protection	CI/CD
GitLab merge request reports and CI example	GitLab Code Quality
Dead-code behavior and framework awareness	Dead Code Detection
Security scanning and taint analysis	Security Analysis
Dependency CVEs, uv/npm/pnpm/Poetry/Yarn lockfiles, offline SBOM, and SCA in CI	Dependency Scanning
Digest-pinned container-image scanning and GitHub Action setup	Container-image scanning
Source GPU contracts and built-artifact preflight	Release Reliability
Rule ID prefixes and product terminology	Rule Dictionary
Agent scan, verification, remediation, and model setup	AI Features
AI defense checks and LLM guardrails	AI Defense
MCP server setup	MCP Server
Real-world merged cleanup PRs	Real-World Results
Baselines, filtering, suppressions, and whitelists	Configuration
Smart tracing	Smart Tracing
Rule families and language support	Rules Reference
Cloud uploads and dashboard flow	CLI to Dashboard
VS Code extension	VS Code Extension
Benchmarks and methodology	BENCHMARK.md
Security policy	SECURITY.md
Release process	RELEASE_WORKFLOW.md
Contribution priorities	ROADMAP.md
Contributing	CONTRIBUTING.md

Common Questions

Does Skylos replace Bandit, Semgrep, CodeQL, or Vulture?

No. Skylos can run alongside them. It focuses on framework-aware dead-code signal, PR gating, AI-era regression checks, and a combined workflow across dead code, security, secrets, quality, and AI-defect checks.

Does Skylos require an LLM?

No. Core static analysis runs locally without API keys. LLM features are optional through skylos[llm] and agent commands.

Does Skylos replace Ruff?

No. skylos lint is an optional convenience entry point that delegates to Ruff. Install it with pip install "skylos[lint]"; normal Skylos scans do not run Ruff or merge Ruff violations into SKY-* findings.

Can I use it only on changed code?

Yes. Use skylos . -a --diff origin/main locally or configure CI gates to focus on new findings.

How should I handle intentional dynamic code?

Use baselines, whitelists, inline suppressions, or runtime tracing. See the configuration docs and smart tracing docs.

Contributing And Support

• Report security issues through SECURITY.md.
• Open bugs and false-positive reports with minimal repros.
• Check ROADMAP.md for useful contribution areas.
• Read CONTRIBUTING.md before sending a pull request.
• See QUALITY.md for project quality and gate expectations.
• Join the Discord for community support.

License

Skylos is licensed under the Apache License 2.0.