diff --git a/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.1_Task_Report.md b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.1_Task_Report.md
new file mode 100644
index 00000000..a192a0c5
--- /dev/null
+++ b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.1_Task_Report.md
@@ -0,0 +1,5 @@
+# R1.1 报告
+
+- 复现输入包含空 `metadata`、空数组和嵌套空数组。
+- Bun YAML 输出 `metadata: `、`spec: ` 和 `items: ` 等尾随空格。
+- `git diff --no-index --check` 稳定以非零状态报告 trailing whitespace。
diff --git a/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.2_Task_Report.md b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.2_Task_Report.md
new file mode 100644
index 00000000..33661729
--- /dev/null
+++ b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.2_Task_Report.md
@@ -0,0 +1,5 @@
+# R1.2 报告
+
+- 在通用 `pacSourceArtifactYaml()` 中仅规范 block scalar 外的 mapping 容器头空白。
+- 未修改 AgentRun 或 HWLAB consumer 文件及渲染职责。
+- 输出前重新解析并逐字段对比原对象；任何漂移均以脱敏摘要失败闭合。
diff --git a/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.3_Task_Report.md b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.3_Task_Report.md
new file mode 100644
index 00000000..e79c8fa3
--- /dev/null
+++ b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.3_Task_Report.md
@@ -0,0 +1,7 @@
+# R1.3 报告
+
+- 定向测试：26 项通过，0 项失败，共 297 个断言。
+- AgentRun 与 HWLAB 首次生成均成功，第二次写入均为 `mutation=false`。
+- 三个真实生成文件均可解析、无行尾空格、EOF 恰好一个换行。
+- 两个 consumer 的 `source-artifact check` 均返回 aligned。
+- 多行 script 的行尾双空格、tab 与伪结构文本保持字节一致。
diff --git a/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.4_Task_Report.md b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.4_Task_Report.md
new file mode 100644
index 00000000..ae378dec
--- /dev/null
+++ b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1.4_Task_Report.md
@@ -0,0 +1,7 @@
+# R1.4 报告
+
+- 交付分支：`fix/1753-pac-yaml-trailing-space`。
+- 关联 issue：https://github.com/pikasTech/unidesk/issues/1753
+- PR：https://github.com/pikasTech/unidesk/pull/1754
+- 受控 preflight：`MERGEABLE`、`CLEAN`、`readyForCommanderMerge=true`。
+- 不执行合并或部署。
diff --git a/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1_Task_Report.md b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1_Task_Report.md
new file mode 100644
index 00000000..29763313
--- /dev/null
+++ b/docs/MDTODO/details/pac-source-artifact-yaml-whitespace/R1_Task_Report.md
@@ -0,0 +1,5 @@
+# R1 总报告
+
+- 通用 PaC source artifact YAML serializer 已仅在结构表示层消除 Bun 容器头行尾空格。
+- 多行 scalar 内容、YAML 结构、一个 EOF 换行和重复生成幂等均已验证。
+- AgentRun 与 HWLAB consumer 无需手工修补。
diff --git a/docs/MDTODO/pac-source-artifact-yaml-whitespace.md b/docs/MDTODO/pac-source-artifact-yaml-whitespace.md
new file mode 100644
index 00000000..33f49bb3
--- /dev/null
+++ b/docs/MDTODO/pac-source-artifact-yaml-whitespace.md
@@ -0,0 +1,25 @@
+# PaC Source Artifact YAML 空白稳定性
+
+- 来源：https://github.com/pikasTech/unidesk/issues/1753
+- 范围：通用 PaC source artifact serializer；禁止 consumer 手工修补。
+
+
+## R1 [completed]
+
+修复 PaC source artifact YAML serializer 的行尾空格，关联 https://github.com/pikasTech/unidesk/issues/1753，完成任务后将详细报告写入[任务报告](./details/pac-source-artifact-yaml-whitespace/R1_Task_Report.md)。
+
+### R1.1 [completed]
+
+复现空 mapping 行尾空格和 git diff --check 失败，关联 https://github.com/pikasTech/unidesk/issues/1753，完成任务后将详细报告写入[任务报告](./details/pac-source-artifact-yaml-whitespace/R1.1_Task_Report.md)。
+
+### R1.2 [completed]
+
+在通用 serializer 修复稳定 YAML 输出并保持结构不变，完成任务后将详细报告写入[任务报告](./details/pac-source-artifact-yaml-whitespace/R1.2_Task_Report.md)。
+
+### R1.3 [completed]
+
+验证 AgentRun/HWLAB 生成、EOF 和二次写入幂等，完成任务后将详细报告写入[任务报告](./details/pac-source-artifact-yaml-whitespace/R1.3_Task_Report.md)。
+
+### R1.4 [completed]
+
+提交非 draft PR、运行受控 preflight 并留下审查证据，完成任务后将详细报告写入[任务报告](./details/pac-source-artifact-yaml-whitespace/R1.4_Task_Report.md)。
diff --git a/scripts/src/platform-infra-pipelines-as-code-source-artifact.test.ts b/scripts/src/platform-infra-pipelines-as-code-source-artifact.test.ts
index 4ca363e1..6891b0c6 100644
--- a/scripts/src/platform-infra-pipelines-as-code-source-artifact.test.ts
+++ b/scripts/src/platform-infra-pipelines-as-code-source-artifact.test.ts
@@ -11,6 +11,7 @@ import {
   canonicalSha256,
   canonicalizePacPipelineSpec,
   firstPacSourceArtifactDrift,
+  pacSourceArtifactSafeError,
   pacValueEvidence,
   pacSourceArtifactYaml,
   parsePacSourceArtifactOptions,
@@ -270,6 +271,75 @@ describe("source artifact serialization", () => {
     expect(first).toContain("apiVersion: tekton.dev/v1\nkind: Pipeline\n");
     expect(Bun.YAML.parse(first)).toEqual(manifest);
   });
+
+  test("empty mappings and sequences have stable whitespace without changing structure", () => {
+    const manifest = {
+      apiVersion: "tekton.dev/v1",
+      kind: "PipelineRun",
+      metadata: {},
+      spec: { params: [], workspaces: [], pipelineSpec: { tasks: [] } },
+    };
+    const serialized = pacSourceArtifactYaml(manifest);
+    expect(serialized).not.toMatch(/[\t ]+$/m);
+    expect(serialized.endsWith("\n")).toBe(true);
+    expect(serialized.endsWith("\n\n")).toBe(false);
+    expect(Bun.YAML.parse(serialized)).toEqual(manifest);
+  });
+
+  test("multi-line script scalar preserves trailing spaces and tabs exactly", () => {
+    const script = [
+      "#!/bin/sh  ",
+      "printf 'mapping-looking scalar: '  ",
+      "metadata: ",
+      "  {}",
+      "printf 'tab follows'\t",
+      "",
+    ].join("\n");
+    const manifest = {
+      apiVersion: "tekton.dev/v1",
+      kind: "Pipeline",
+      metadata: { name: "scalar-round-trip" },
+      spec: { tasks: [{ name: "build", taskSpec: { steps: [{ name: "build", script }] } }] },
+    };
+    const serialized = pacSourceArtifactYaml(manifest);
+    const parsed = Bun.YAML.parse(serialized) as typeof manifest;
+    expect(parsed).toEqual(manifest);
+    expect(parsed.spec.tasks[0]?.taskSpec.steps[0]?.script).toBe(script);
+    expect(Buffer.from(parsed.spec.tasks[0]?.taskSpec.steps[0]?.script ?? "")).toEqual(Buffer.from(script));
+    expect(serialized.endsWith("\n")).toBe(true);
+    expect(serialized.endsWith("\n\n")).toBe(false);
+  });
+
+  test("round-trip failure exposes only secret-safe drift evidence", () => {
+    const secret = "ROUND_TRIP_SCRIPT_SECRET_DO_NOT_PRINT";
+    let reads = 0;
+    const spec: Record<string, unknown> = {};
+    Object.defineProperty(spec, "script", {
+      enumerable: true,
+      get: () => {
+        reads += 1;
+        return reads <= 2 ? secret : "changed-after-serialization";
+      },
+    });
+
+    let thrown: unknown;
+    try {
+      pacSourceArtifactYaml({ apiVersion: "tekton.dev/v1", kind: "Pipeline", spec });
+    } catch (error) {
+      thrown = error;
+    }
+    expect(thrown).toBeInstanceOf(Error);
+    const safe = pacSourceArtifactSafeError(thrown);
+    const serializedError = JSON.stringify({
+      message: thrown instanceof Error ? thrown.message : String(thrown),
+      direct: thrown,
+      safe,
+    });
+    expect(safe.code).toBe("source-artifact-yaml-round-trip-failed");
+    expect(serializedError).not.toContain(secret);
+    expect(serializedError).not.toContain("changed-after-serialization");
+    expect(serializedError).toContain("sha256");
+  });
 });
 
 describe("runtime source-commit selection", () => {
diff --git a/scripts/src/platform-infra-pipelines-as-code-source-artifact.ts b/scripts/src/platform-infra-pipelines-as-code-source-artifact.ts
index ab099f76..1f81253d 100644
--- a/scripts/src/platform-infra-pipelines-as-code-source-artifact.ts
+++ b/scripts/src/platform-infra-pipelines-as-code-source-artifact.ts
@@ -1032,7 +1032,33 @@ function parseYamlRecord(text: string, label: string): Record<string, unknown> {
 }
 
 export function pacSourceArtifactYaml(value: Record<string, unknown>): string {
-  return `${Bun.YAML.stringify(value, null, 2).trim()}\n`;
+  const lines = Bun.YAML.stringify(value, null, 2).split("\n");
+  let blockScalarHeaderIndent: number | null = null;
+  const normalized = lines.map((line) => {
+    const content = line.trim();
+    const indent = line.length - line.trimStart().length;
+    if (blockScalarHeaderIndent !== null) {
+      if (content.length === 0 || indent > blockScalarHeaderIndent) return line;
+      blockScalarHeaderIndent = null;
+    }
+
+    const structuralLine = line.replace(/:[\t ]+$/u, ":");
+    if (/(?:^|:[\t ]+|-[\t ]+)[|>](?:[1-9][+-]?|[+-][1-9]?|[+-])?[\t ]*(?:#.*)?$/u.test(structuralLine)) {
+      blockScalarHeaderIndent = indent;
+    }
+    return structuralLine;
+  }).join("\n");
+  const withSingleEofNewline = `${normalized.replace(/\n+$/u, "")}\n`;
+  const roundTrip = parseYamlRecord(withSingleEofNewline, "serialized source artifact");
+  const roundTripDrift = firstCanonicalDrift(value, roundTrip, "$");
+  if (roundTripDrift !== null) {
+    throw new PacSourceArtifactError("source-artifact-yaml-round-trip-failed", {
+      driftPath: roundTripDrift.path,
+      expectedEvidence: roundTripDrift.expected,
+      actualEvidence: roundTripDrift.actual,
+    });
+  }
+  return withSingleEofNewline;
 }
 
 function requiredParam(binding: PacSourceArtifactBinding, key: string): string {