diff --git a/src/reportChannels/reportChannel.ts b/src/reportChannels/reportChannel.ts
index 06f71f9..c07a250 100644
--- a/src/reportChannels/reportChannel.ts
+++ b/src/reportChannels/reportChannel.ts
@@ -1,3 +1,4 @@
+import { appendFile } from "node:fs/promises"
 import {
   DISCORD_WEBHOOK_URL_ENV_NAME,
   type ReportChannelInput,
@@ -9,6 +10,91 @@ import {
   type DiscordMessage
 } from "./discordMessageSplitter.js"
 
+const GITHUB_STEP_SUMMARY_ENV_NAME = "GITHUB_STEP_SUMMARY"
+
+type AppendFileOperation = (
+  path: string,
+  content: string,
+  encoding: BufferEncoding
+) => Promise<void>
+
+type WorkflowReportDeliveryOptions = ReportChannelOptions & {
+  githubStepSummaryPath?: string
+  appendFile?: AppendFileOperation
+}
+
+type WorkflowReportDeliveryResult =
+  | { ok: true }
+  | {
+      ok: false
+      errorMessage: string
+    }
+
+// workflow에서는 Actions summary 또는 stdout을 기본으로 기록하고 Discord를 추가 전송
+export async function deliver(
+  input: ReportChannelInput,
+  options: WorkflowReportDeliveryOptions = {}
+): Promise<WorkflowReportDeliveryResult> {
+  if (!input.markdown.trim()) {
+    return {
+      ok: true
+    }
+  }
+
+  const errorMessages: string[] = []
+  const summaryPath = options.githubStepSummaryPath ??
+    process.env[GITHUB_STEP_SUMMARY_ENV_NAME]
+
+  if (summaryPath?.trim()) {
+    const summaryResult = await sendGitHubActionsSummary(
+      input.markdown,
+      summaryPath,
+      options
+    )
+
+    if (!summaryResult.ok) {
+      errorMessages.push(summaryResult.errorMessage)
+
+      const stdoutResult = await sendStdout(input.markdown, options)
+
+      if (!stdoutResult.ok) {
+        errorMessages.push(
+          `stdout report write failed: ${stdoutResult.errorMessage}`
+        )
+      }
+    }
+  } else {
+    const stdoutResult = await sendStdout(input.markdown, options)
+
+    if (!stdoutResult.ok) {
+      errorMessages.push(
+        `stdout report write failed: ${stdoutResult.errorMessage}`
+      )
+    }
+  }
+
+  const webhookUrl = options.discordWebhookUrl ?? process.env[DISCORD_WEBHOOK_URL_ENV_NAME]
+
+  if (webhookUrl) {
+    const discordResult = await sendDiscord(input.markdown, webhookUrl, options)
+
+    if (!discordResult.ok) {
+      errorMessages.push(discordResult.errorMessage)
+    }
+  }
+
+  if (0 < errorMessages.length) {
+    return {
+      ok: false,
+      errorMessage: errorMessages.join("\n")
+    }
+  }
+
+  return {
+    ok: true
+  }
+}
+
 // Discord webhook URL이 있으면 Discord channel로 보내고 없으면 stdout으로 fallback
 export async function send(
   input: ReportChannelInput,
@@ -55,6 +141,27 @@ async function sendStdout(
   }
 }
 
+// GitHub Actions가 제공한 step summary 파일에 전체 Markdown report를 추가 기록
+async function sendGitHubActionsSummary(
+  markdown: string,
+  path: string,
+  options: WorkflowReportDeliveryOptions
+): Promise<WorkflowReportDeliveryResult> {
+  try {
+    const write = options.appendFile ?? appendFile
+    await write(path, `${markdown}\n`, "utf8")
+
+    return {
+      ok: true
+    }
+  } catch (error) {
+    return {
+      ok: false,
+      errorMessage: `GitHub Actions summary write failed: ${errorMessageFor(error)}`
+    }
+  }
+}
+
 // Discord content 제한을 넘지 않도록 Markdown report를 여러 메시지로 나눠 전송
 async function sendDiscord(
   markdown: string,
diff --git a/src/workflows/mergeRiskWatch.ts b/src/workflows/mergeRiskWatch.ts
index 843c4e0..3e943df 100644
--- a/src/workflows/mergeRiskWatch.ts
+++ b/src/workflows/mergeRiskWatch.ts
@@ -18,7 +18,7 @@ import { build as buildAiPredictionPairRequests } from "../ai/predictionPairRequ
 import { predict as predictBranchPairsWithAi } from "../ai/predictionPairRunner.js"
 import { build as buildBranchPairMergeRiskReport } from "../reports/branchPairReportBuilder.js"
 import { format as formatBranchPairMergeRiskReportMarkdown } from "../reports/branchPairMarkdownFormatter.js"
-import { send as sendMergeRiskReport } from "../reportChannels/reportChannel.js"
+import { deliver as deliverMergeRiskReport } from "../reportChannels/reportChannel.js"
 import {
   sanitizeAiPredictionPairFailureDebugEvent,
   sanitizeAiPredictionPairPromptDebugEvent,
@@ -51,6 +51,7 @@ type MergeRiskWatchOptions = {
   debugArtifactDir?: string
   workflowRef?: string
   fetch?: typeof fetch
+  reportDeliveryOptions?: Parameters<typeof deliverMergeRiskReport>[1]
 }
 
 type RemoteBranchLine = {
@@ -243,9 +244,9 @@ export async function run(options: MergeRiskWatchOptions): Promise<void> {
     aiResults: predictions
   })
   const markdown = formatBranchPairMergeRiskReportMarkdown(report)
-  const result = await sendMergeRiskReport({
+  const result = await deliverMergeRiskReport({
     markdown
-  })
+  }, options.reportDeliveryOptions)
 
   if (!result.ok) {
     throw new Error(result.errorMessage)
diff --git a/tests/reportChannels/reportChannel.test.ts b/tests/reportChannels/reportChannel.test.ts
index a8d9860..2c3d740 100644
--- a/tests/reportChannels/reportChannel.test.ts
+++ b/tests/reportChannels/reportChannel.test.ts
@@ -3,6 +3,264 @@ import assert from "node:assert/strict"
 import {
   sendMergeRiskReport
 } from "../../src/index.js"
+import {
+  deliver as deliverMergeRiskReport
+} from "../../src/reportChannels/reportChannel.js"
+
+// GitHub Actions에서는 전체 Markdown report를 step summary에 기록하는지 확인
+test("writes full report to GitHub Actions summary", async () => {
+  const appendFile = new AppendFileSpy()
+  const stdout = new StdoutSpy()
+  const markdown = reportWithTwoPairFragments()
+  const result = await deliverMergeRiskReport({
+    markdown
+  }, {
+    discordWebhookUrl: "",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: appendFile.write,
+    stdout
+  })
+
+  assert.deepEqual(result, {
+    ok: true
+  })
+  assert.deepEqual(appendFile.writes, [{
+    path: "/tmp/github-step-summary",
+    content: `${markdown}\n`
+  }])
+  assert.equal(stdout.output, "")
+})
+
+// 주입 경로가 없어도 Actions 환경 변수의 summary 경로를 사용하는지 확인
+test("reads GitHub Actions summary path from environment", async () => {
+  const appendFile = new AppendFileSpy()
+  const originalSummaryPath = process.env.GITHUB_STEP_SUMMARY
+  process.env.GITHUB_STEP_SUMMARY = "/tmp/github-step-summary-from-env"
+
+  try {
+    const result = await deliverMergeRiskReport({
+      markdown: "## Merge Risk Report"
+    }, {
+      discordWebhookUrl: "",
+      appendFile: appendFile.write
+    })
+
+    assert.deepEqual(result, {
+      ok: true
+    })
+    assert.deepEqual(appendFile.writes, [{
+      path: "/tmp/github-step-summary-from-env",
+      content: "## Merge Risk Report\n"
+    }])
+  } finally {
+    if (originalSummaryPath === undefined) {
+      delete process.env.GITHUB_STEP_SUMMARY
+    } else {
+      process.env.GITHUB_STEP_SUMMARY = originalSummaryPath
+    }
+  }
+})
+
+// Discord 설정이 있어도 Actions summary와 Discord에 report를 모두 전달하는지 확인
+test("writes Actions summary and sends Discord report", async () => {
+  const appendFile = new AppendFileSpy()
+  const fetcher = fetchSpy({})
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: appendFile.write,
+    fetch: fetcher
+  })
+
+  assert.deepEqual(result, {
+    ok: true
+  })
+  assert.deepEqual(appendFile.writes, [{
+    path: "/tmp/github-step-summary",
+    content: "## Merge Risk Report\n"
+  }])
+  assert.equal(fetcher.requests.length, 1)
+})
+
+// Actions summary 경로가 없으면 stdout과 설정된 Discord에 모두 전달하는지 확인
+test("falls back to stdout and sends Discord report outside Actions", async () => {
+  const fetcher = fetchSpy({})
+  const stdout = new StdoutSpy()
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "",
+    fetch: fetcher,
+    stdout
+  })
+
+  assert.deepEqual(result, {
+    ok: true
+  })
+  assert.equal(stdout.output, "## Merge Risk Report\n")
+  assert.equal(fetcher.requests.length, 1)
+})
+
+// 빈 Markdown report는 Actions summary, stdout, Discord 어디에도 쓰지 않는지 확인
+test("skips every workflow report delivery for empty report", async () => {
+  const appendFile = new AppendFileSpy()
+  const fetcher = fetchSpy({})
+  const stdout = new StdoutSpy()
+  const result = await deliverMergeRiskReport({
+    markdown: " \n\t"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: appendFile.write,
+    fetch: fetcher,
+    stdout
+  })
+
+  assert.deepEqual(result, {
+    ok: true
+  })
+  assert.deepEqual(appendFile.writes, [])
+  assert.equal(fetcher.requests.length, 0)
+  assert.equal(stdout.output, "")
+})
+
+// Actions summary 기록이 실패해도 stdout fallback과 Discord 전송을 계속하는지 확인
+test("continues stdout and Discord delivery after summary failure", async () => {
+  const fetcher = fetchSpy({})
+  const stdout = new StdoutSpy()
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: async () => {
+      throw new Error("summary unavailable")
+    },
+    fetch: fetcher,
+    stdout
+  })
+
+  assert.deepEqual(result, {
+    ok: false,
+    errorMessage: "GitHub Actions summary write failed: summary unavailable"
+  })
+  assert.equal(stdout.output, "## Merge Risk Report\n")
+  assert.equal(fetcher.requests.length, 1)
+})
+
+// Discord 전송이 실패해도 Actions summary에 전체 report가 남는지 확인
+test("keeps Actions summary when Discord delivery fails", async () => {
+  const appendFile = new AppendFileSpy()
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: appendFile.write,
+    fetch: fetchSpy({}, {
+      ok: false,
+      status: 500
+    })
+  })
+
+  assert.deepEqual(result, {
+    ok: false,
+    errorMessage: "Discord webhook request for report fragment 1 failed with status 500"
+  })
+  assert.deepEqual(appendFile.writes, [{
+    path: "/tmp/github-step-summary",
+    content: "## Merge Risk Report\n"
+  }])
+})
+
+// Actions summary와 Discord가 모두 실패하면 두 channel 오류를 순서대로 반환하는지 확인
+test("reports summary and Discord delivery failures together", async () => {
+  const fetcher = fetchSpy({}, {
+    ok: false,
+    status: 500
+  })
+  const stdout = new StdoutSpy()
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: async () => {
+      throw new Error("summary unavailable")
+    },
+    fetch: fetcher,
+    stdout
+  })
+
+  assert.deepEqual(result, {
+    ok: false,
+    errorMessage: [
+      "GitHub Actions summary write failed: summary unavailable",
+      "Discord webhook request for report fragment 1 failed with status 500"
+    ].join("\n")
+  })
+  assert.equal(stdout.output, "## Merge Risk Report\n")
+  assert.equal(fetcher.requests.length, 1)
+})
+
+// summary, stdout fallback, Discord가 모두 실패하면 오류를 전달 순서대로 반환하는지 확인
+test("reports summary stdout and Discord failures in order", async () => {
+  const fetcher = fetchSpy({}, {
+    ok: false,
+    status: 500
+  })
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "/tmp/github-step-summary",
+    appendFile: async () => {
+      throw new Error("summary unavailable")
+    },
+    fetch: fetcher,
+    stdout: {
+      write: () => {
+        throw new Error("stdout unavailable")
+      }
+    }
+  })
+
+  assert.deepEqual(result, {
+    ok: false,
+    errorMessage: [
+      "GitHub Actions summary write failed: summary unavailable",
+      "stdout report write failed: stdout unavailable",
+      "Discord webhook request for report fragment 1 failed with status 500"
+    ].join("\n")
+  })
+  assert.equal(fetcher.requests.length, 1)
+})
+
+// local stdout 실패가 설정된 Discord 전송을 막지 않는지 확인
+test("continues Discord delivery after stdout failure", async () => {
+  const fetcher = fetchSpy({})
+  const result = await deliverMergeRiskReport({
+    markdown: "## Merge Risk Report"
+  }, {
+    discordWebhookUrl: "https://discord.test/webhook",
+    githubStepSummaryPath: "",
+    fetch: fetcher,
+    stdout: {
+      write: () => {
+        throw new Error("stdout unavailable")
+      }
+    }
+  })
+
+  assert.deepEqual(result, {
+    ok: false,
+    errorMessage: "stdout report write failed: stdout unavailable"
+  })
+  assert.equal(fetcher.requests.length, 1)
+})
 
 // Discord webhook URL이 없으면 Markdown report를 stdout으로 출력하는지 확인
 test("sends report to stdout when discord webhook is missing", async () => {
@@ -347,6 +605,20 @@ class StdoutSpy {
   }
 }
 
+class AppendFileSpy {
+  readonly writes: Array<{
+    path: string
+    content: string
+  }> = []
+
+  readonly write = async (path: string, content: string): Promise<void> => {
+    this.writes.push({
+      path,
+      content
+    })
+  }
+}
+
 type FetchSpy = typeof fetch & {
   requests: Array<{
     url: string
diff --git a/tests/workflows/mergeRiskWatch.test.ts b/tests/workflows/mergeRiskWatch.test.ts
index d351c36..46e44d9 100644
--- a/tests/workflows/mergeRiskWatch.test.ts
+++ b/tests/workflows/mergeRiskWatch.test.ts
@@ -216,6 +216,7 @@ test("predicts confirmed conflict pair once", async () => {
   const fixture = await createWorkflowGitFixture({
     peerContent: "peer critical content\n"
   })
+  const summaryPath = join(fixture.debugArtifactDir, "summary.md")
   const originalFetch = globalThis.fetch
   const originalOpenAiApiKey = process.env.OPENAI_API_KEY
   const originalDiscordWebhookUrl = process.env.DISCORD_WEBHOOK_URL
@@ -247,16 +248,22 @@ test("predicts confirmed conflict pair once", async () => {
       githubToken: undefined,
       repositoryPath: fixture.repositoryPath,
       baseBranch: "main",
-      debugArtifactDir: fixture.debugArtifactDir
+      debugArtifactDir: fixture.debugArtifactDir,
+      reportDeliveryOptions: {
+        githubStepSummaryPath: summaryPath
+      }
     })
 
     const resultArtifact = await readFile(
       join(fixture.debugArtifactDir, "ai-result.json"),
       "utf8"
     )
+    const summaryReport = await readFile(summaryPath, "utf8")
 
     assert.equal(openAiRequestCount, 1)
     assert.match(discordReport, /resolved critical content/)
+    assert.match(summaryReport, /`feature\/critical` ↔ `feature\/critical-peer`/)
+    assert.match(summaryReport, /resolved critical content/)
     assert.doesNotMatch(resultArtifact, /resolved critical content/)
     assert.equal((await readdir(fixture.debugArtifactDir)).includes("report.md"), false)
   } finally {
@@ -267,6 +274,58 @@ test("predicts confirmed conflict pair once", async () => {
   }
 })
 
+// Actions summary 기록 실패 후에도 stdout과 Discord report를 남기고 workflow를 실패시키는지 확인
+test("propagates summary failure after fallback report delivery", async () => {
+  const fixture = await createWorkflowGitFixture({
+    separateHunks: true
+  })
+  const originalFetch = globalThis.fetch
+  const originalOpenAiApiKey = process.env.OPENAI_API_KEY
+  const originalDiscordWebhookUrl = process.env.DISCORD_WEBHOOK_URL
+  let discordRequestCount = 0
+  let stdoutReport = ""
+
+  delete process.env.OPENAI_API_KEY
+  process.env.DISCORD_WEBHOOK_URL = "https://discord.test/webhook-secret"
+  globalThis.fetch = async input => {
+    assert.equal(new Request(input).url, "https://discord.test/webhook-secret")
+    discordRequestCount += 1
+    return new Response(null, { status: 204 })
+  }
+
+  try {
+    await assert.rejects(
+      run({
+        ...baseOptions(),
+        githubToken: undefined,
+        repositoryPath: fixture.repositoryPath,
+        baseBranch: "main",
+        reportDeliveryOptions: {
+          githubStepSummaryPath: join(fixture.debugArtifactDir, "summary.md"),
+          appendFile: async () => {
+            throw new Error("summary unavailable")
+          },
+          stdout: {
+            write: value => {
+              stdoutReport += String(value)
+              return true
+            }
+          }
+        }
+      }),
+      /GitHub Actions summary write failed: summary unavailable/
+    )
+
+    assert.match(stdoutReport, /## Merge Risk Report/)
+    assert.equal(0 < discordRequestCount, true)
+  } finally {
+    globalThis.fetch = originalFetch
+    restoreEnv("OPENAI_API_KEY", originalOpenAiApiKey)
+    restoreEnv("DISCORD_WEBHOOK_URL", originalDiscordWebhookUrl)
+    await fixture.remove()
+  }
+})
+
 // provider 오류 원문이 실패 artifact에 기록되지 않는지 확인
 test("redacts provider error detail from debug artifacts", async () => {
   const fixture = await createWorkflowGitFixture()
@@ -544,7 +603,13 @@ function baseOptions() {
     baseBranch: "develop",
     remoteName: "origin",
     githubApiUrl: "https://api.github.test",
-    githubToken: "github-token"
+    githubToken: "github-token",
+    reportDeliveryOptions: {
+      githubStepSummaryPath: "",
+      stdout: {
+        write: () => true
+      }
+    }
   }
 }