diff --git a/LOCAL_AWS_SETUP.md b/LOCAL_AWS_SETUP.md
index 2fc338ffed2a..65b6226c36ef 100644
--- a/LOCAL_AWS_SETUP.md
+++ b/LOCAL_AWS_SETUP.md
@@ -172,6 +172,7 @@ See [flexion/opencode#2](https://github.com/flexion/opencode/pull/2) for the ful
 |--------|---------|-------------|
 | Hide skill prompt text from chat UI | `packages/opencode/src/session/prompt.ts` | Marks skill template as `synthetic` so the full prompt is sent to the model but hidden from the user |
 | Respect `tool_call: false` at runtime | `packages/opencode/src/session/llm.ts` | Gates tool resolution behind `capabilities.toolcall` — fixes failures on Bedrock models that don't support streaming + tool use |
+| Re-sign macOS binaries after build | `packages/opencode/script/build.ts` | Strips Bun's embedded signature and applies a fresh ad-hoc one — fixes SIGKILL (exit 137) on Darwin 25+ where Bun's signature format is rejected |
 | Local build & AWS Bedrock setup docs | `LOCAL_AWS_SETUP.md` | This file |
 
 Full details and upstream tracking: [flexion/opencode#2](https://github.com/flexion/opencode/pull/2)
diff --git a/packages/opencode/script/build.ts b/packages/opencode/script/build.ts
index 6d1087f2873e..bc23c940847d 100755
--- a/packages/opencode/script/build.ts
+++ b/packages/opencode/script/build.ts
@@ -232,6 +232,14 @@ for (const item of targets) {
     },
   })
 
+  // On macOS, Bun's embedded code signature is rejected by Darwin 25+.
+  // Strip it and apply a fresh ad-hoc signature so the binary can run.
+  if (item.os === "darwin") {
+    const binaryPath = `dist/${name}/bin/opencode`
+    await $`codesign --remove-signature ${binaryPath}`.quiet()
+    await $`codesign --sign - --force ${binaryPath}`.quiet()
+  }
+
   // Smoke test: only run if binary is for current platform
   if (item.os === process.platform && item.arch === process.arch && !item.abi) {
     const binaryPath = `dist/${name}/bin/opencode`