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Add tree-sitter structural diff for code files #1982

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d608c4b
Add tree-sitter structural diff for code files
SamMorrowDrums Feb 9, 2026
317c44c
Fix Docker build: statically link CGO binary for distroless
SamMorrowDrums Feb 9, 2026
4b0cd4c
Add inline diffs and recursive nesting for structural diff
SamMorrowDrums Feb 9, 2026
d8ed060
Extract names from var/const declarations in Go
SamMorrowDrums Feb 9, 2026
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3 changes: 1 addition & 2 deletions .goreleaser.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,11 @@ before:

builds:
- env:
- CGO_ENABLED=0
- CGO_ENABLED=1
ldflags:
- -s -w -X main.version={{.Version}} -X main.commit={{.Commit}} -X main.date={{.Date}}
goos:
- linux
- windows
- darwin
main: ./cmd/github-mcp-server
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Copilot AI Feb 9, 2026

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This PR enables CGO in release builds and removes Windows from GoReleaser targets, but the repo CI still runs script/test and go build on windows-latest. Since go-tree-sitter requires CGO (and Windows runners typically lack a GCC/Clang toolchain by default), the Windows CI job will likely fail. Consider either (1) adding build tags + a !cgo stub that falls back to unified diffs, so non-CGO builds still compile, or (2) updating CI to drop Windows or install a working CGO toolchain there.

Copilot uses AI. Check for mistakes.

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6 changes: 3 additions & 3 deletions Dockerfile
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Expand Up @@ -4,16 +4,16 @@ ARG VERSION="dev"
# Set the working directory
WORKDIR /build

# Install git
# Install git and C compiler for CGO (tree-sitter)
RUN --mount=type=cache,target=/var/cache/apk \
apk add git
apk add git gcc musl-dev

# Build the server
# go build automatically download required module dependencies to /go/pkg/mod
RUN --mount=type=cache,target=/go/pkg/mod \
--mount=type=cache,target=/root/.cache/go-build \
--mount=type=bind,target=. \
CGO_ENABLED=0 go build -ldflags="-s -w -X main.version=${VERSION} -X main.commit=$(git rev-parse HEAD) -X main.date=$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
CGO_ENABLED=1 go build -ldflags="-s -w -linkmode external -extldflags '-static' -X main.version=${VERSION} -X main.commit=$(git rev-parse HEAD) -X main.date=$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
-o /bin/github-mcp-server ./cmd/github-mcp-server

# Make a stage to run the app
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2 changes: 2 additions & 0 deletions go.mod
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Expand Up @@ -13,6 +13,8 @@ require (
github.com/stretchr/testify v1.11.1
)

require github.com/smacker/go-tree-sitter v0.0.0-20240827094217-dd81d9e9be82

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Copilot AI Feb 9, 2026

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go.mod is not in the usual go mod tidy canonical form: the new direct dependency is in its own single-line require block. Since CI runs go mod tidy -diff, this is likely to fail. Please re-run go mod tidy so the dependency is merged into the main direct-requires block and any indirects are updated accordingly.

Suggested change
)
require github.com/smacker/go-tree-sitter v0.0.0-20240827094217-dd81d9e9be82
github.com/smacker/go-tree-sitter v0.0.0-20240827094217-dd81d9e9be82
)

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require (
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Copilot AI Feb 9, 2026

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A new third-party dependency is introduced here. This repo’s CI includes script/licenses-check, which regenerates and diffs third-party-licenses.*.md and third-party/; without committing the regenerated outputs, the license-check workflow will fail. Please run ./script/licenses and commit any updated license artifacts alongside the dependency change.

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github.com/aymerick/douceur v0.2.0 // indirect
github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
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2 changes: 2 additions & 0 deletions go.sum
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Expand Up @@ -74,6 +74,8 @@ github.com/shurcooL/githubv4 v0.0.0-20240727222349-48295856cce7 h1:cYCy18SHPKRkv
github.com/shurcooL/githubv4 v0.0.0-20240727222349-48295856cce7/go.mod h1:zqMwyHmnN/eDOZOdiTohqIUKUrTFX62PNlu7IJdu0q8=
github.com/shurcooL/graphql v0.0.0-20230722043721-ed46e5a46466 h1:17JxqqJY66GmZVHkmAsGEkcIu0oCe3AM420QDgGwZx0=
github.com/shurcooL/graphql v0.0.0-20230722043721-ed46e5a46466/go.mod h1:9dIRpgIY7hVhoqfe0/FcYp0bpInZaT7dc3BYOprrIUE=
github.com/smacker/go-tree-sitter v0.0.0-20240827094217-dd81d9e9be82 h1:6C8qej6f1bStuePVkLSFxoU22XBS165D3klxlzRg8F4=
github.com/smacker/go-tree-sitter v0.0.0-20240827094217-dd81d9e9be82/go.mod h1:xe4pgH49k4SsmkQq5OT8abwhWmnzkhpgnXeekbx2efw=
github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 h1:+jumHNA0Wrelhe64i8F6HNlS8pkoyMv5sreGx2Ry5Rw=
github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8/go.mod h1:3n1Cwaq1E1/1lhQhtRK2ts/ZwZEhjcQeJQ1RuC6Q/8U=
github.com/spf13/afero v1.15.0 h1:b/YBCLWAJdFWJTN9cLhiXXcD7mzKn9Dm86dNnfyQw1I=
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6 changes: 3 additions & 3 deletions pkg/github/compare_file_contents_test.go
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Expand Up @@ -114,7 +114,7 @@ func Test_CompareFileContents(t *testing.T) {
expectDiff: `host: "localhost" → "production.db"`,
},
{
name: "unsupported format falls back to unified diff",
name: "Go file uses structural diff",
mockedClient: MockHTTPClientWithHandlers(map[string]http.HandlerFunc{
GetReposContentsByOwnerByRepoByPath: mockContentsForRef(map[string]string{
"main": "func main() {}\n",
Expand All @@ -128,8 +128,8 @@ func Test_CompareFileContents(t *testing.T) {
"base": "main",
"head": "feature",
},
expectFormat: "unified",
expectDiff: "--- a/main.go",
expectFormat: "structural",
expectDiff: "function_declaration main: modified",
},
{
name: "missing required parameter - owner",
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7 changes: 7 additions & 0 deletions pkg/github/semantic_diff.go
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Expand Up @@ -80,6 +80,10 @@ func SemanticDiff(path string, base, head []byte) SemanticDiffResult {
case ".toml":
return semanticDiffTOML(path, base, head)
default:
// Try tree-sitter structural diff for code files
if languageForPath(path) != nil {
return structuralDiff(path, base, head)
}
return SemanticDiffResult{
Format: DiffFormatUnified,
Diff: unifiedDiff(path, base, head),
Expand Down Expand Up @@ -542,6 +546,9 @@ func DetectDiffFormat(path string) DiffFormat {
case ".toml":
return DiffFormatTOML
default:
if languageForPath(path) != nil {
return DiffFormatStructural
}
return DiffFormatUnified
}
}
43 changes: 12 additions & 31 deletions pkg/github/semantic_diff_test.go
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Expand Up @@ -302,36 +302,17 @@ func TestSemanticDiffTOML(t *testing.T) {
}

func TestSemanticDiffUnifiedFallback(t *testing.T) {
tests := []struct {
name string
path string
base string
head string
expectedDiff string
}{
{
name: "unsupported extension uses unified diff",
path: "main.go",
base: "func main() {\n}\n",
head: "func main() {\n\tfmt.Println(\"hello\")\n}\n",
expectedDiff: "--- a/main.go",
},
{
name: "no extension uses unified diff",
path: "Makefile",
base: "all:\n\techo hello\n",
head: "all:\n\techo world\n",
expectedDiff: "--- a/Makefile",
},
}
t.Run("Go file uses structural diff", func(t *testing.T) {
result := SemanticDiff("main.go", []byte("func main() {\n}\n"), []byte("func main() {\n\tfmt.Println(\"hello\")\n}\n"))
assert.Equal(t, DiffFormatStructural, result.Format)
assert.Contains(t, result.Diff, "function_declaration main: modified")
})

for _, tc := range tests {
t.Run(tc.name, func(t *testing.T) {
result := SemanticDiff(tc.path, []byte(tc.base), []byte(tc.head))
assert.Equal(t, DiffFormatUnified, result.Format)
assert.Contains(t, result.Diff, tc.expectedDiff)
})
}
t.Run("no extension uses unified diff", func(t *testing.T) {
result := SemanticDiff("Makefile", []byte("all:\n\techo hello\n"), []byte("all:\n\techo world\n"))
assert.Equal(t, DiffFormatUnified, result.Format)
assert.Contains(t, result.Diff, "--- a/Makefile")
})
}

func TestSemanticDiffFileSizeLimit(t *testing.T) {
Expand Down Expand Up @@ -373,7 +354,7 @@ func TestSemanticDiffNewAndDeletedFiles(t *testing.T) {

t.Run("deleted Go file", func(t *testing.T) {
result := SemanticDiff("main.go", []byte("package main\n"), nil)
assert.Equal(t, DiffFormatUnified, result.Format)
assert.Equal(t, DiffFormatStructural, result.Format)
assert.Equal(t, "file deleted", result.Diff)
})

Expand All @@ -394,7 +375,7 @@ func TestDetectDiffFormat(t *testing.T) {
{"config.yml", DiffFormatYAML},
{"data.csv", DiffFormatCSV},
{"config.toml", DiffFormatTOML},
{"main.go", DiffFormatUnified},
{"main.go", DiffFormatStructural},
{"README.md", DiffFormatUnified},
{"Makefile", DiffFormatUnified},
}
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