[#42] baseBranch를 포함한 branch 비교 조합을 구성한다

README.md

@@ -151,6 +151,7 @@ artifact에는 다음 파일이 포함됩니다.
 | --- | --- |
 | `run.json` | repository, base branch, default branch, critical file patterns, Watcher workflow ref |
 | `branch-selection.json` | 수집된 branch, 감시 대상 branch, 제외된 branch와 사유 |
+| `branch-pairs.json` | base branch와 감시 대상 branch 전체의 이름순 비교 조합 |
 | `deterministic-evidence.json` | git merge signal, changed files, changed hunks, check/PR metadata, deterministic risk 결과 |
 | `ai-target-selection.json` | AI 호출 대상 branch와 skipped branch 사유 |
 | `ai-prompt.json` | OpenAI에 전달한 system prompt, user prompt, response shape |

src/branches/branchPairBuilder.ts

@@ -0,0 +1,46 @@
+import type {
+  BranchComparisonPair,
+  BranchContext
+} from "./types.js"
+
+// base branch와 활성 branch에서 중복 없는 비교 조합을 이름순으로 구성
+export function build(
+  baseBranch: string,
+  branches: BranchContext[]
+): BranchComparisonPair[] {
+  const branchNames = [...new Set([
+    baseBranch,
+    ...branches.map(branch => branch.name)
+  ])].sort(compareBranchNames)
+  const pairs: BranchComparisonPair[] = []
+
+  for (let leftIndex = 0; leftIndex < branchNames.length; leftIndex += 1) {
+    const leftBranchName = branchNames[leftIndex]!
+
+    for (
+      let rightIndex = leftIndex + 1;
+      rightIndex < branchNames.length;
+      rightIndex += 1
+    ) {
+      pairs.push({
+        leftBranchName,
+        rightBranchName: branchNames[rightIndex]!
+      })
+    }
+  }
+
+  return pairs
+}
+
+// 실행 환경에 무관한 문자열 비교로 branch 이름 순서를 결정
+function compareBranchNames(branchName: string, otherBranchName: string): number {
+  if (branchName < otherBranchName) {
+    return -1
+  }
+
+  if (otherBranchName < branchName) {
+    return 1
+  }
+
+  return 0
+}

src/branches/types.ts

@@ -42,6 +42,11 @@ export type BranchSelectionResult = {
   excluded: ExcludedBranch[]
 }
 
+export type BranchComparisonPair = {
+  leftBranchName: string
+  rightBranchName: string
+}
+
 export type BranchContext = {
   baseBranch: string
   name: string

src/workflows/mergeRiskWatch.ts

@@ -2,6 +2,7 @@ import { execFile } from "node:child_process"
 import { fileURLToPath } from "node:url"
 import { resolve } from "node:path"
 import { promisify } from "node:util"
+import { build as buildBranchComparisonPairs } from "../branches/branchPairBuilder.js"
 import { selectWithReasons as selectBranchesWithReasons } from "../branches/branchSelector.js"
 import { collectGitMergeSignal } from "../git/gitMergeSignalCollector.js"
 import { analyze as analyzeBranchMergeRisks } from "../risks/riskAnalyzer.js"
@@ -125,13 +126,17 @@ export async function run(options: MergeRiskWatchOptions): Promise<void> {
     defaultBranch: options.defaultBranch
   }, generatedAt)
   const branches = branchSelection.selected
+  const pairs = buildBranchComparisonPairs(options.baseBranch, branches)
   const inputs: BranchRiskAnalysisInput[] = []
 
   await debugArtifactWriter?.writeJson("branch-selection.json", {
     repositoryBranches,
     selectedBranches: branchSelection.selected,
     excludedBranches: branchSelection.excluded
   })
+  await debugArtifactWriter?.writeJson("branch-pairs.json", {
+    pairs
+  })
 
   for (const branch of branches) {
     const gitSignal = await collectGitMergeSignal(branch, {

tests/branches/branchPairBuilder.test.ts

@@ -0,0 +1,104 @@
+import test from "node:test"
+import assert from "node:assert/strict"
+import { build } from "../../src/branches/branchPairBuilder.js"
+import type { BranchContext } from "../../src/branches/types.js"
+
+// 활성 branch가 없으면 비교 조합을 만들지 않는지 확인
+test("returns no pairs without active branches", () => {
+  assert.deepEqual(build("main", []), [])
+})
+
+// base branch와 활성 branch 하나를 한 번만 조합하는지 확인
+test("pairs the base branch with one active branch", () => {
+  assert.deepEqual(build("develop", [branch("feature/watch", "develop")]), [{
+    leftBranchName: "develop",
+    rightBranchName: "feature/watch"
+  }])
+})
+
+// 중복 이름과 자기 자신 조합을 제외하고 방향 없는 조합만 만드는지 확인
+test("excludes duplicate, self, and reversed pairs", () => {
+  const pairs = build("main", [
+    branch("feature/b"),
+    branch("feature/a"),
+    branch("feature/a"),
+    branch("main")
+  ])
+
+  assert.deepEqual(pairs, [{
+    leftBranchName: "feature/a",
+    rightBranchName: "feature/b"
+  }, {
+    leftBranchName: "feature/a",
+    rightBranchName: "main"
+  }, {
+    leftBranchName: "feature/b",
+    rightBranchName: "main"
+  }])
+})
+
+// 입력 순서와 무관하게 branch 이름 기준의 같은 조합 순서를 만드는지 확인
+test("builds pairs in deterministic branch name order", () => {
+  const pairs = build("main", [
+    branch("feature/z"),
+    branch("feature/a"),
+    branch("feature/m")
+  ])
+  const reorderedPairs = build("main", [
+    branch("feature/m"),
+    branch("feature/z"),
+    branch("feature/a")
+  ])
+
+  assert.deepEqual(reorderedPairs, pairs)
+  assert.deepEqual(pairs[0], {
+    leftBranchName: "feature/a",
+    rightBranchName: "feature/m"
+  })
+  assert.deepEqual(pairs.at(-1), {
+    leftBranchName: "feature/z",
+    rightBranchName: "main"
+  })
+})
+
+// 지역화 규칙이 아닌 문자열 비교로 대소문자 branch 순서를 고정하는지 확인
+test("uses non-localized string comparison", () => {
+  const pairs = build("main", [
+    branch("feature/a"),
+    branch("feature/Z")
+  ])
+
+  assert.deepEqual(pairs, [{
+    leftBranchName: "feature/Z",
+    rightBranchName: "feature/a"
+  }, {
+    leftBranchName: "feature/Z",
+    rightBranchName: "main"
+  }, {
+    leftBranchName: "feature/a",
+    rightBranchName: "main"
+  }])
+})
+
+// 활성 branch 30개와 base branch에서 최대 465개 조합을 만드는지 확인
+test("builds 465 pairs for 30 active branches", () => {
+  const branches = Array.from({ length: 30 }, (_, index) =>
+    branch(`feature/${String(index).padStart(2, "0")}`)
+  )
+
+  const pairs = build("main", branches)
+
+  assert.equal(pairs.length, 465)
+  assert.equal(new Set(pairs.map(pair =>
+    `${pair.leftBranchName}\u0000${pair.rightBranchName}`
+  )).size, 465)
+})
+
+function branch(name: string, baseBranch = "main"): BranchContext {
+  return {
+    baseBranch,
+    name,
+    headSha: `${name}-sha`,
+    checks: []
+  }
+}

tests/workflows/mergeRiskWatch.test.ts

@@ -125,6 +125,7 @@ test("writes merge risk debug artifacts", async () => {
       "ai-response.json",
       "ai-result.json",
       "ai-target-selection.json",
+      "branch-pairs.json",
       "branch-selection.json",
       "deterministic-evidence.json",
       "report.md",
@@ -157,6 +158,12 @@ test("writes merge risk debug artifacts", async () => {
         reason?: string
       }>
     }>(fixture.debugArtifactDir, "branch-selection.json")
+    const branchPairsArtifact = await readJson<{
+      pairs?: Array<{
+        leftBranchName?: string
+        rightBranchName?: string
+      }>
+    }>(fixture.debugArtifactDir, "branch-pairs.json")
     const combinedArtifact = (await Promise.all(files.map(file =>
       readFile(join(fixture.debugArtifactDir, file), "utf8")
     ))).join("\n")
@@ -186,6 +193,16 @@ test("writes merge risk debug artifacts", async () => {
       name: "main",
       reason: "base_branch"
     }])
+    assert.deepEqual(branchPairsArtifact.pairs, [{
+      leftBranchName: "feature/critical",
+      rightBranchName: "feature/critical-peer"
+    }, {
+      leftBranchName: "feature/critical",
+      rightBranchName: "main"
+    }, {
+      leftBranchName: "feature/critical-peer",
+      rightBranchName: "main"
+    }])
     assert.doesNotMatch(combinedArtifact, /openai-secret/)
     assert.doesNotMatch(combinedArtifact, /webhook-secret/)
     assert.doesNotMatch(combinedArtifact, /feature critical content/)