olt — Odin Language Tools

A Clippy-inspired static analyser for the Odin programming language. Catches memory leaks, double-frees, naming violations, unchecked errors, and more — before the compiler or runtime does.

$ olt src/
🔴 src/core/main.odin:42:5: C001 [correctness] Allocation without matching defer free
Fix: Add 'defer delete(buf)' immediately after the allocation
🔴 src/api/handlers.odin:18:9: C201 [correctness] error return of 'os.open' is discarded
1 violation(s) in 2 file(s)

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Install

Pre-built binaries

Download from Releases for your platform, then:

olt setup        # OLS detection → install → MCP registration (3-step wizard)

Build from source

Requires Odin dev-2026-05 or newer.

git clone --recurse-submodules https://github.com/RainerXE/odintooling
cd odintooling
./scripts/build.sh        # → artifacts/macos-arm64/olt

First-run setup

olt setup        # full system setup — runs the 3-step wizard below
olt init         # create olt.toml in a project directory

olt setup is a 3-step wizard:

Step 1 — OLS — detects OLS in PATH (both ols and ols_lsp / Homebrew). Lets you confirm or override the path.

Step 2 — Install — copies olt to ~/.local/bin/ and creates three symlinks that enable argv[0] dispatch:

• ols → olt — point your editor here instead of vanilla OLS
• olt-lsp → olt — backward-compat LSP name
• olt-mcp → olt — backward-compat MCP name

Step 3 — MCP — detects installed AI coding tools and registers olt-mcp in each one's config file automatically. Supports:

Tool	Config file written
Claude Code	claude mcp add (CLI)
Cursor	~/.cursor/mcp.json
Cline	…/saoudrizwan.claude-dev/settings/cline_mcp_settings.json
Codex	~/.codex/config.toml
OpenCode	~/.config/opencode/opencode.json
Antigravity	~/.gemini/antigravity/mcp_config.json
Hermes Agent	~/.hermes/config.yaml

Config paths resolve correctly on macOS, Linux, and Windows. If a tool's config directory isn't at the expected location, the wizard asks for it.

olt init checks whether setup has been run and offers to run it first if needed.

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Usage

olt src/                      # lint a directory (recursive)
olt file.odin                 # lint a single file
olt src/ --fix                # apply safe auto-fixes in-place
olt src/ --format json        # machine-readable output (json or sarif)
olt src/ --rule C001,C201     # run specific rules only
olt src/ --tier correctness   # run only correctness-tier rules
olt --explain C001            # detailed rule documentation
olt --list-rules              # show all available rules

olt mcp                       # start MCP server (AI agent interface)
olt lsp                       # start LSP proxy (editor interface)

Exit codes

Code	Meaning
0	No violations
1	One or more violations
2	Usage error or internal failure

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Rules

Correctness

Rule	What it catches
C001	Heap allocation (make/new) without defer delete/defer free
C002	Double-free or use-after-free
C009	Deprecated core:os/old import — use core:os
C010	Small_Array superseded by [dynamic; N]T
C011	FFI C resource (ts_*_new) without matching defer ts_*_delete
C101	context.allocator reassigned without defer restore
C201	Error return value discarded (unchecked result)
C202	Switch on enum not exhaustive (requires --export-symbols)
C203	defer in inner block fires before outer scope uses the handle

Style

Rule	What it catches
C003	Procedure names must be snake_case
C007	Type/struct/enum names must be PascalCase
C016	Local variable names must be snake_case (default on)
C031	panic() on expected runtime failure — consider error return (INFO)
C034	for v, _ in collection — blank index unnecessary (INFO, auto-fix)
C037	Trailing return at end of void procedure (INFO, auto-fix)

Opt-in domains

Enable in olt.toml:

Domain	Rules	What it enables
stdlib_safety = true	C029, C033	strings.split/clone/join, fmt.aprintf, os.read_entire_file without defer delete; strings.builder_make without defer strings.builder_destroy
go_migration = true	C021–C023, C025	Go-style fmt.Println, for i,v := range, *ptr deref, append(s,v) without &
semantic_naming = true	C012	Ownership naming hints (_ptr, _owned, etc.)
dead_code = true	C014, C015	Unexported procedures and constants never referenced
ffi = true	C011	FFI resource safety (auto-detected if ffi/ directory exists)

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Configuration — olt.toml

Run olt init in your project directory to generate one, or create it manually:

[domains]
ffi           = true   # C011: FFI resource safety
odin_2026     = true   # C009/C010: deprecated API detection
stdlib_safety = true   # C029/C033: stdlib allocation safety

[naming]
c016 = true   # local variables must be snake_case
c019 = false  # type marker suffixes (opt-in)
c020 = false  # minimum name length (opt-in)
c020_min_length = 3
c020_allowed    = "i,j,k,x,y,z,n,ok,err,db,id"

[tools]
ols_path = "/usr/local/bin/ols_lsp"   # path to OLS (if not in PATH)

Inline suppression

buf := make([]u8, n)  // olt:ignore C001 arena-managed, freed by caller

Multiple rules: // olt:ignore C001,C002

Legacy alias // odin-lint:ignore is also accepted.

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Editor integration

olt lsp is an LSP proxy: your editor talks to it as the single Odin language server. It forwards everything to vanilla OLS (completions, hover, go-to-definition) and injects olt diagnostics into the diagnostic stream.

After olt setup, an ols symlink is created pointing to olt. Point your editor at that symlink — no other changes needed.

VS Code (settings.json):

"odin.languageServer.path": "/path/to/ols"

Helix (languages.toml):

[[language]]
name = "odin"
language-servers = ["ols"]

[language-server.ols]
command = "/path/to/ols"

Neovim (lspconfig):

require('lspconfig').ols.setup { cmd = { '/path/to/ols' } }

OLS must be installed separately: github.com/DanielGavin/ols. Homebrew installs it as ols_lsp — olt setup detects both names automatically.

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AI agent integration

olt mcp exposes olt as an MCP server for Claude Code and other AI agents.

olt setup registers olt-mcp automatically for every detected tool (see First-run setup).

For manual registration, add to your tool's MCP config file — the binary is ~/.local/bin/olt-mcp after setup:

{
  "mcpServers": {
    "olt-mcp": { "command": "/Users/you/.local/bin/olt-mcp", "args": [] }
  }
}

Codex (~/.codex/config.toml):

[mcp_servers.olt_mcp]
command = "/Users/you/.local/bin/olt-mcp"
enabled = true

Hermes Agent (~/.hermes/config.yaml):

mcp_servers:
  olt-mcp:
    command: /Users/you/.local/bin/olt-mcp
    args: []

Available MCP tools:

Tool	Description
lint_file	Lint a file on disk
lint_snippet	Lint in-memory source text
lint_fix	Return proposed fixes as JSON
lint_workspace	Batch-lint a directory
list_rules	Return the full rule catalog as JSON
run_odin_check	Run odin check and return compiler diagnostics
get_symbol	Look up a symbol in the code graph
export_symbols	Build the code knowledge graph
get_dna_context	Callers, callees, memory role for a proc
get_impact_radius	Transitive impact of changing a symbol
get_callers / get_callees	Direct call graph neighbours
search_symbols	Full-text symbol search
rename_symbol	Generate rename patches across the project

Code knowledge graph

Build a semantic graph of your project for deeper analysis:

olt src/ --export-symbols

By default this writes to .codegraph/odin_lint_graph.db and .codegraph/symbols.json. The .codegraph/ directory is a shared convention — other code intelligence tools (e.g. CodeGraph) also use it, each with their own filename, so they coexist without conflict.

Pass a custom path via the MCP export_symbols tool:

{ "path": "src/", "db_path": "/tmp/my_project.db" }

symbols_path in the response is always derived from db_path — /tmp/my_project.db → /tmp/symbols.json.

Add .codegraph/ to your .gitignore to keep generated graph files out of version control:

.codegraph/

Once exported, this enables:

• C202 switch exhaustiveness checking
• All get_* / search_symbols MCP tools for AI-assisted refactoring

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Architecture

                ┌─────────────────────────────┐
                │           olt               │
                │  argv[0] / subcommand       │
                │  dispatch                   │
                └──────┬──────────┬───────────┘
                       │          │
              ┌────────┴──┐  ┌────┴──────┐
              │  olt lsp  │  │  olt mcp  │
              │  (editor) │  │  (agent)  │
              └────────┬──┘  └───────────┘
                       │
                  shared rule engine
                  analyze_content()
                       │
                  C001–C203 rules

Symlinks created by olt setup:

• ols → olt — IDE OLS integration (argv[0] dispatch → LSP mode)
• olt-lsp → olt — backward compat
• olt-mcp → olt — backward compat

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Project layout

src/main.odin      Unified entry point (argv[0] + subcommand dispatch)
src/core/          Rule engine, CLI, config parsing, graph DB
src/mcp/           MCP server tools
src/lsp/           LSP proxy
ffi/tree_sitter/   Tree-sitter grammar + static libraries
ffi/sqlite/        SQLite static library
vendor/odin-mcp    MCP protocol library (https://github.com/RainerXE/odin-mcp)
tests/             Rule test fixtures
scripts/           Build and test scripts

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Contributing

Run the full test suite before submitting:

./scripts/run_c001_tests.sh
./scripts/run_c002_tests.sh
# ... see scripts/run_*.sh for all rule suites
./artifacts/macos-arm64/olt src/   # must produce 0 violations

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License

MIT

"The miracle is this: The more we share the more we have." — Leonard Nimoy