Osnova

Osnova

A deterministic code map for AI coding agents. Osnova indexes a repository into a symbol and call graph with tree-sitter, then serves it to any MCP client or from the command line. Same input, same output, byte for byte. No embeddings, no telemetry, and no network connection unless you type osnova update-check. Twenty languages, seven of them (TypeScript, JavaScript, Python, Go, Rust, Java, C#) with deep adapters.

*Osnova* is the Slavic word for base or foundation. That is the job: give an agent solid ground to stand on before it edits code.

Quick start

Node.js 22.13 or newer. Serve a repository to any MCP client:

npx -y @getdomovoi/osnova mcp --workspace /path/to/repo

After npm install -g @getdomovoi/osnova, one command per kind of agent: claude wires Claude Code (MCP entry, session, prompt and stop hooks, and the skill); agents wires every installed harness that reads AGENTS.md (Codex, OpenCode, Kilo, Pi, Cursor), each with its hooks, plugin or extension, plus one shared skill in ~/.agents/skills/. Each previews its changes; --apply writes them, backing up every file it changes.

osnova setup claude --apply

osnova setup agents --apply

Or add the MCP entry by hand; replace osnova with npx -y @getdomovoi/osnova when there is no global install.

{ "mcpServers": { "osnova": { "command": "osnova", "args": ["mcp"] } } }

What you get back

osnova warp src/api.ts#refreshWorkspace on this repository, cut to twelve lines (test/docs-readme-warp.test.ts fails when the first two no longer reproduce):

function src/api.ts#refreshWorkspace: 83 indexed edges

reach: d1 callers 83 in 14 files (3 dirs); d2 +16 in 2 files; unresolved same-name 10; tests 18 d1 calls src/cli/cli.ts#ensureIndex:78 [import-binding] d1 calls src/cli/hook.ts#runHook:191,203,225,240 [import-binding] d1 calls src/mcp/server.ts#createOsnovaMcpServer.refresh:297 [import-binding] d1 calls test/verification-fastpath.test.ts# :37,47,48,51,53,57,58,64,68,74,78,85,110,114,132,145,154,166,171,197 [re-export-binding] via src/index.ts:65 refreshWorkspace -> src/api.ts (export refreshWorkspace) This does not prove absence of callers or that deletion is safe. unresolved evidence (10); not confirmed relationships candidates for refreshWorkspace (2, unverified): src/api.ts#refreshWorkspace, test/mcp-watch.test.ts#refreshWorkspace d1 calls refreshWorkspace test/artifact-format9.test.ts:78,85,104,120,140 [binding-blocked] d1 calls refreshWorkspace scripts/perf.mjs:485,486,491 [import-target-unresolved]

Each confirmed line names the caller, its lines and the evidence that tied the call to this definition: an import binding, a same-file definition, a re-export chain with its hop, or an identified receiver. Calls the index could not tie to a definition are listed apart as unresolved evidence, with the same-name candidates it found and the reason it stopped, so a name match is never mistaken for a caller. The reach line gives exact counts, not scores, and when the list outgrows its budget a capped: line and an omitted: footer count what was left out.

How much of the graph is exact

A call site counts as resolved when the index ties it to one definition through evidence it can name; everything else stays unresolved with a reason. These are the shares on the pinned checkouts under benchmarks/corpora/, recorded in benchmarks/results/resolution-coverage-2026-09-21b.json; the last column leaves out calls through packages outside the repository and calls to builtins, which can never resolve locally, and the reference defines every column.

Per-language rows are in the reference. osnova coverage reports the same numbers for your own repository, per language and per reason.

Resolved is not the same as right, so the call edges are also scored against each language's type checker or compiler. Every call site in six pinned checkouts was sent to the checker for the callee's declarations, and each osnova edge was marked true when the definition it names contains that declaration and false when it does not. Measured at 0.12.0:

Java and C# overloads share one symbol in the index, so a call edge names the overload it binds only when the written argument count fits exactly one declaration of the type, its partial parts and its declared base classes; when it fits several or none, the edge keeps the method and names no declaration, and the oracle leaves it out of both rates (2526 edges on gson, 602 on humanizer). 0.11.0 named the last overload declared for every call, recorded a call at the first line of its call expression, and lost the rest of a C# file after a primary constructor or a raw string; it measured gson 2045 false edges (24.75%), humanizer 617 (8.25%) and ripgrep 112 (2.06%). Of the 29 left on ripgrep, 11 are functions declared once per #[cfg] branch, 6 are a test module's function named like its parent's, and 5 are calls to a local closure or parameter named like a function elsewhere. A call whose target has one declaration that fits keeps it even when a base type is outside the index, where an unseen base overload could be the one the compiler binds; this limit is kept because withdrawing those edges cost 10 recall points on humanizer for one fewer false edge. Every false edge is classified by cause in benchmarks/results/type-checker-oracle-2026-09-30.json with the method and its limits. The scripts that produce these numbers are in benchmarks/oracle/.

Grep versus the graph

The reason to keep a call graph instead of running a text search is not speed. It is that the first regex a person types is wrong more often than it looks, and nobody notices. Nine call-site sets in six languages were verified line by line; each cell shows sites found (precision / recall), and the method lists what each side got wrong.

The graph never returned a site that was not a call of the target. The record is benchmarks/results/grep-vs-graph-2026-09-21.json.

The ten tools

The names play on the foundation image. The CLI uses the same names without the prefix: osnova ground and osnova_ground are the same query.