blackwell-systems / lsp-cross-repo

Name: blackwell-systems/lsp-cross-repo
Author: blackwell-systems

Cross-repository analysis — find all callers of a library symbol in one or more consumer repos. Use when refactoring a shared library and need to understand how consumers use it.

Version

SKILL.md

4.3 KB

Requires the agent-lsp MCP server.

lsp-cross-repo

Multi-root cross-repo caller analysis for library + consumer workflows. Finds all
usages of a library symbol across one or more consumer codebases in a single call.

Read-only — does not modify any files.

When to use

Before changing a library API: find all callers in every consumer
Before deleting a symbol: verify it has no cross-repo dependents
When a change in repo A might break repo B or C
Auditing how internal packages are used across services

Use /lsp-impact instead for single-repo blast-radius analysis.

Workflow

Step 1 — Initialize the primary workspace

Start the language server on the library root if not already running:

mcp__lsp__start_lsp({ "root_dir": "/path/to/library" })

Step 2 — Locate the library symbol

Find the symbol's definition to get file_path, line, and column:

mcp__lsp__find_symbol({ "query": "<symbol-name>" })

Pick the result in the library repo (not a test file).

Step 3 — Find all cross-repo references (primary step)

Call get_cross_repo_references with the symbol location and all consumer repo
roots. This adds each consumer as a workspace folder, waits for indexing, runs
find_references across all roots, and returns results partitioned by repo:

mcp__lsp__get_cross_repo_references({
  "symbol_file": "/abs/path/to/library/file.go",
  "line": <line>,
  "column": <column>,
  "consumer_roots": [
    "/abs/path/to/consumer-a",
    "/abs/path/to/consumer-b"
  ]
})

Returns:

library_references — usages within the library itself
consumer_references — a map of consumer-root → [file:line ...]
warnings — any roots that could not be indexed (check these manually)

Decision after Step 3:

Result	Action
No consumer refs	Safe to change — verify `warnings` is empty first
Consumer refs found	Run `/lsp-impact` on each call site before editing
`warnings` non-empty	Re-add that root manually and retry Step 3

Step 4 — Callers and implementations (optional)

For a deeper look at how consumers call the symbol:

mcp__lsp__find_callers({
  "file_path": "<library-file>",
  "line": <line>,
  "column": <column>,
  "direction": "incoming"
})

For interfaces — all consumer-side implementations:

mcp__lsp__go_to_implementation({
  "file_path": "<library-file>",
  "line": <line>,
  "column": <column>
})

Output format

## Library-internal references
- file:line — brief context

## Consumer references

### /path/to/consumer-a
- file:line — brief context

### /path/to/consumer-b
- file:line — brief context

Decision guide

Situation	Action
No consumer refs, warnings empty	Safe to change
Consumer refs found	Run `/lsp-impact` on each call site before editing
`warnings` lists a consumer root	That root failed indexing — check LSP logs
Consumer uses interface, not concrete type	Use `go_to_implementation` to find all implementors

Example

# Refactoring ParseConfig in a shared config library used by 3 services

start_lsp(root_dir="/repos/config-lib")
find_symbol(query="ParseConfig")        # find definition → file:42:6
get_cross_repo_references(
  symbol_file="/repos/config-lib/pkg/config/parser.go",
  line=42, column=6,
  consumer_roots=["/repos/api-service", "/repos/worker-service", "/repos/batch-job"]
)
# → library_references: 2
# → consumer_references: {api-service: [main.go:14, app.go:31], worker-service: [runner.go:8]}
# → warnings: []