diff --git a/examples/acp-agent/cordis.yml b/examples/acp-agent/cordis.yml
index 48760828e2..a6889114fd 100644
--- a/examples/acp-agent/cordis.yml
+++ b/examples/acp-agent/cordis.yml
@@ -113,11 +113,13 @@
 # results under the session cwd, and the post-execute policy that replaces the
 # model-facing result with a bounded preview + read path. Snapshots lower the
 # cap so a deterministic bash result exercises this transcript surface without a
-# real model call; normal demo runs keep the coding-agent cap.
+# real model call. The snapshot harness supplies a fixed spill root so the
+# spill-policy preview budget is stable across macOS/Linux path lengths; normal
+# demo runs keep the session-local `.spill` root and the coding-agent cap.
 - id: spill-local
   name: '@deepseek-ai/dsh-spill-local'
   config:
-    root: ./.spill
+    root: !!js process.env.DSH_SNAPSHOT_SPILL_ROOT ?? './.spill'
 
 - id: spill-policy
   name: '@deepseek-ai/dsh-spill-policy'
diff --git a/examples/acp-agent/tests/snapshots/bash-spill/session.jsonl b/examples/acp-agent/tests/snapshots/bash-spill/session.jsonl
index 7c7fe12630..aa60d5143e 100644
--- a/examples/acp-agent/tests/snapshots/bash-spill/session.jsonl
+++ b/examples/acp-agent/tests/snapshots/bash-spill/session.jsonl
@@ -10,7 +10,7 @@
 {"type":"assistant/chunk","seq":8,"time":0,"data":{"turn":1,"step":1,"chunk":{"type":"finish","reason":{"kind":"tool-calls"}}}}
 {"type":"assistant/message","seq":9,"time":0,"data":{"turn":1,"step":1,"content":[{"type":"tool-call","id":"call_spill","name":"bash","arguments":"{\"command\":\"node -e \\\"process.stdout.write('SPILL_START-' + 'x'.repeat(2000) + '-SPILL_END')\\\"\",\"description\":\"Print large deterministic output\"}"}],"usage":{"inputTokens":10,"outputTokens":5}},"sourceEventSeqs":[4,5,6,7,8],"surfaceOp":"append"}
 {"type":"tool/call","seq":10,"time":0,"data":{"turn":1,"step":1,"callId":"call_spill","name":"bash","arguments":"{\"command\":\"node -e \\\"process.stdout.write('SPILL_START-' + 'x'.repeat(2000) + '-SPILL_END')\\\"\",\"description\":\"Print large deterministic output\"}"}}
-{"type":"tool/result","seq":11,"time":0,"data":{"turn":1,"step":1,"callId":"call_spill","content":[{"type":"text","text":"SPILL_START-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-SPILL_END\n\n(Omitted 1447 bytes. Full formatted result saved to: {{spillPath:bash.txt}}. Use read with offset/limit to inspect it.)"}],"isError":false},"sourceEventSeqs":[10],"surfaceOp":"append"}
+{"type":"tool/result","seq":11,"time":0,"data":{"turn":1,"step":1,"callId":"call_spill","content":[{"type":"text","text":"SPILL_START-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-SPILL_END\n\n(Omitted 1391 bytes. Full formatted result saved to: {{spillPath:bash.txt}}. Use read with offset/limit to inspect it.)"}],"isError":false},"sourceEventSeqs":[10],"surfaceOp":"append"}
 {"type":"step/end","seq":12,"time":0,"data":{"turn":1,"step":1}}
 {"type":"step/start","seq":13,"time":0,"data":{"turn":1,"step":2}}
 {"type":"assistant/chunk","seq":14,"time":0,"data":{"turn":1,"step":2,"chunk":{"type":"block-start","index":0,"blockType":"text"}}}
diff --git a/examples/acp-agent/tests/snapshots/bash-spill/stdout.golden.jsonl b/examples/acp-agent/tests/snapshots/bash-spill/stdout.golden.jsonl
index dfd9c4fb2b..df47558232 100644
--- a/examples/acp-agent/tests/snapshots/bash-spill/stdout.golden.jsonl
+++ b/examples/acp-agent/tests/snapshots/bash-spill/stdout.golden.jsonl
@@ -1,6 +1,6 @@
 {"jsonrpc":"2.0","id":1,"result":{"protocolVersion":1,"agentInfo":{"name":"deepseek-harness-acp","version":"0.0.1"},"agentCapabilities":{"loadSession":true,"promptCapabilities":{"image":false,"audio":false,"embeddedContext":false}},"authMethods":[]}}
 {"jsonrpc":"2.0","id":2,"result":{"sessionId":"{{sessionId}}"}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call","toolCallId":"call_spill","title":"node -e \"process.stdout.write('SPILL_START-' + 'x'.repeat(2000) + '-SPILL_END')\"","kind":"execute","status":"in_progress","rawInput":"node -e \"process.stdout.write('SPILL_START-' + 'x'.repeat(2000) + '-SPILL_END')\"","content":[{"type":"content","content":{"type":"text","text":"Print large deterministic output"}}]}}}
-{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_spill","status":"completed","content":[{"type":"content","content":{"type":"text","text":"```console\nSPILL_START-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-SPILL_END\n\n(Omitted 1447 bytes. Full formatted result saved to: {{spillPath:bash.txt}}. Use read with offset/limit to inspect it.)\n```"}}]}}}
+{"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"tool_call_update","toolCallId":"call_spill","status":"completed","content":[{"type":"content","content":{"type":"text","text":"```console\nSPILL_START-xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx-SPILL_END\n\n(Omitted 1391 bytes. Full formatted result saved to: {{spillPath:bash.txt}}. Use read with offset/limit to inspect it.)\n```"}}]}}}
 {"jsonrpc":"2.0","method":"session/update","params":{"sessionId":"{{sessionId}}","update":{"sessionUpdate":"agent_message_chunk","content":{"type":"text","text":"DONE"}}}}
 {"jsonrpc":"2.0","id":3,"result":{"stopReason":"end_turn"}}
diff --git a/packages/support/acp-snapshot/src/harness.ts b/packages/support/acp-snapshot/src/harness.ts
index 538b81d57e..befcf32dca 100644
--- a/packages/support/acp-snapshot/src/harness.ts
+++ b/packages/support/acp-snapshot/src/harness.ts
@@ -180,6 +180,9 @@ export interface RunOptions {
 export async function runScenario(input: InputScript, opts: RunOptions): Promise<RunResult> {
   const cwd = await mkdtemp(join(tmpdir(), 'acp-snap-cwd-'))
   const sessionsRoot = await mkdtemp(join(tmpdir(), 'acp-snap-sessions-'))
+  // Fixed path length: spill-policy budgets the preview against the REAL path
+  // before stdout normalization, so tmpdir() length differences churn goldens.
+  const spillRoot = '/tmp/dsh-acp-snapshot-spill'
   // Everything past the temp-dir creation runs under a try/finally that always
   // removes both dirs — so a failure in workspace seeding, spawn, or any step
   // never leaks them (the "e2e tests own their resources" rule).
@@ -201,6 +204,7 @@ export async function runScenario(input: InputScript, opts: RunOptions): Promise
       DSH_SNAPSHOT: opts.mode,
       DSH_SNAPSHOT_FILE: opts.fixtureFile,
       DSH_SNAPSHOT_SESSIONS_ROOT: sessionsRoot,
+      DSH_SNAPSHOT_SPILL_ROOT: spillRoot,
       ...opts.overrideFile !== undefined ? { DSH_SNAPSHOT_OVERRIDE: opts.overrideFile } : {},
       ...opts.childFiles !== undefined && opts.childFiles.length > 0
         ? { DSH_SNAPSHOT_CHILD_FILES: opts.childFiles.join(delimiter) }
@@ -310,6 +314,7 @@ export async function runScenario(input: InputScript, opts: RunOptions): Promise
     }
     await rm(cwd, { recursive: true, force: true })
     await rm(sessionsRoot, { recursive: true, force: true })
+    await rm(spillRoot, { recursive: true, force: true })
   }
 
   return {
diff --git a/packages/support/acp-snapshot/src/normalize.ts b/packages/support/acp-snapshot/src/normalize.ts
index a4ce886f8b..e5b15a4abb 100644
--- a/packages/support/acp-snapshot/src/normalize.ts
+++ b/packages/support/acp-snapshot/src/normalize.ts
@@ -38,6 +38,11 @@ const LOCAL_SPILL_PATH_RE = new RegExp(
   + String.raw`(?=\. Use read with offset/limit|[\s)]|$)`,
   'g',
 )
+const SNAPSHOT_SPILL_PATH_RE = new RegExp(
+  String.raw`/tmp/dsh-acp-snapshot-spill/session-[0-9a-f]{12}/[0-9a-f]{12}-([A-Za-z0-9._~-]+?)`
+  + String.raw`(?=\. Use read with offset/limit|[\s)]|$)`,
+  'g',
+)
 
 /** Inputs the normalizers need to recognize a run's volatile values. */
 export interface NormalizeContext {
@@ -55,6 +60,7 @@ function scrubString(value: string, ctx: NormalizeContext): string {
   out = out.split(ctx.cwd).join(CWD)
   out = out.split(`/private${CWD}`).join(CWD)
   out = out.replace(LOCAL_SPILL_PATH_RE, (_match, name: string) => `{{spillPath:${name}}}`)
+  out = out.replace(SNAPSHOT_SPILL_PATH_RE, (_match, name: string) => `{{spillPath:${name}}}`)
   for (const id of ctx.sessionIds) out = out.split(id).join(SESSION_ID)
   out = out.replace(UUID_RE, SESSION_ID)
   return out
diff --git a/packages/support/acp-snapshot/tests/normalize.spec.ts b/packages/support/acp-snapshot/tests/normalize.spec.ts
index a33436a164..ec388294bf 100644
--- a/packages/support/acp-snapshot/tests/normalize.spec.ts
+++ b/packages/support/acp-snapshot/tests/normalize.spec.ts
@@ -117,6 +117,21 @@ describe('normalizeSessionLog', () => {
     expect(out).not.toContain('/private{{spillPath')
   })
 
+  it('scrubs fixed snapshot spill paths', () => {
+    const ev = JSON.stringify({
+      type: 'tool/result', seq: 2, time: 5,
+      data: {
+        content: [{
+          type: 'text',
+          text: 'Full formatted result saved to: /tmp/dsh-acp-snapshot-spill/session-c22bc3f1d2af/8a7b6c5d4e3f-bash.txt. Use read with offset/limit to inspect it.',
+        }],
+      },
+    })
+    const out = normalizeSessionLog(`${header({ cwd: ctx.cwd })}\n${ev}\n`, ctx)
+    expect(out).toContain('{{spillPath:bash.txt}}')
+    expect(out).not.toContain('/tmp/dsh-acp-snapshot-spill')
+  })
+
   it('scrubs the session id in the header', () => {
     const out = normalizeSessionLog(`${header({ id: ctx.sessionIds[0] })}\n`, ctx)
     expect(out).toContain('{{sessionId}}')