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Local code navigation with Sem

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Local code navigation with Sem

Sem exposes structural code search over stdio MCP. This optional example requires no Sem account or API key and makes no model calls.

The example configuration pins the server version and disables editor imports. It requires an explicit repository path so the server does not accidentally index the configuration directory. The path is also used as the server's working directory; an unset SEM_REPO fails configuration loading before the server starts. The shell guard below also rejects an empty value.

#Run from a checkout

Use Node 24 or 26 and the pnpm version declared in package.json. From the MCPorter repository root:

pnpm install --frozen-lockfile
pnpm build
export SEM_REPO=/absolute/path/to/trusted/git/repository
: "${SEM_REPO:?Set SEM_REPO to an absolute path to a trusted Git repository}"
node dist/cli.js --config examples/sem/mcporter.json list sem --schema

The first invocation downloads the npm package and its native binary. Use a supported macOS or Linux machine (x64 or ARM64). The environment flags force local graph queries, disable Sem cloud sync and telemetry, and start a standalone MCP process instead of reusing a repository daemon that may have cloud access enabled. They do not prevent npm downloads or sandbox the process.

Search for a symbol, then request its context explicitly. Replace parse_config with a symbol in your repository:

node dist/cli.js --config examples/sem/mcporter.json call sem.sem_find \
  --args '{"query":"parse_config"}'

node dist/cli.js --config examples/sem/mcporter.json call sem.sem_find \
  --args '{"query":"parse_config","mode":"context","token_budget":1200}'

Inspect list sem --schema for other arguments. Structural results depend on language support and index coverage; an empty result is not proof that a reference does not exist.

#Scope and safety

  • These example calls only request navigation. The server also exposes sem_check, which can execute repository commands. Use trusted repositories and review calls before execution.
  • SEM_REPO selects a checkout, not an OS-level access boundary. Run untrusted code in a separate sandbox.
  • To integrate with an existing configuration, copy only the sem entry into its mcpServers map and preserve its imports setting. Set SEM_REPO in the environment launching MCPorter.
  • Removing the entry disables the integration but does not remove downloaded packages or repository indexes.