diff --git a/packages/opencode/src/tool/shell.ts b/packages/opencode/src/tool/shell.ts
index 1e4423e01774..1674695938ae 100644
--- a/packages/opencode/src/tool/shell.ts
+++ b/packages/opencode/src/tool/shell.ts
@@ -444,8 +444,6 @@ export const ShellTool = Tool.define(
       let file = ""
       let sink: ReturnType<typeof createWriteStream> | undefined
       let cut = false
-      let expired = false
-      let aborted = false
 
       const closeSink = Effect.fnUntraced(function* () {
         const stream = sink
@@ -478,7 +476,7 @@ export const ShellTool = Tool.define(
         },
       })
 
-      const code: number | null = yield* Effect.scoped(
+      const exit = yield* Effect.scoped(
         Effect.gen(function* () {
           yield* Effect.addFinalizer(closeSink)
           const handle = yield* spawner.spawn(cmd(input.shell, input.command, input.cwd, input.env))
@@ -540,31 +538,35 @@ export const ShellTool = Tool.define(
           const timeout = Effect.sleep(`${input.timeout + 100} millis`)
 
           const exit = yield* Effect.raceAll([
-            handle.exitCode.pipe(Effect.map((code) => ({ kind: "exit" as const, code }))),
+            // Signal termination fails exitCode; raceAll only settles on success.
+            handle.exitCode.pipe(
+              Effect.match({
+                onSuccess: (code: number) => ({ kind: "exit" as const, code }),
+                onFailure: (error) => ({ kind: "error" as const, code: null, error }),
+              }),
+            ),
             abort.pipe(Effect.map(() => ({ kind: "abort" as const, code: null }))),
             timeout.pipe(Effect.map(() => ({ kind: "timeout" as const, code: null }))),
           ])
 
-          if (exit.kind === "abort") {
-            aborted = true
-            yield* handle.kill({ forceKillAfter: "3 seconds" }).pipe(Effect.orDie)
-          }
-          if (exit.kind === "timeout") {
-            expired = true
+          if (exit.kind === "abort" || exit.kind === "timeout") {
             yield* handle.kill({ forceKillAfter: "3 seconds" }).pipe(Effect.orDie)
           }
 
-          return exit.kind === "exit" ? exit.code : null
+          return exit
         }),
       ).pipe(Effect.orDie)
 
       const meta: string[] = []
-      if (expired) {
+      if (exit.kind === "timeout") {
         meta.push(
           `shell tool terminated command after exceeding timeout ${input.timeout} ms. If this command is expected to take longer and is not waiting for interactive input, retry with a larger timeout value in milliseconds.`,
         )
       }
-      if (aborted) meta.push("User aborted the command")
+      if (exit.kind === "abort") meta.push("User aborted the command")
+      if (exit.kind === "error") {
+        meta.push(exit.error.cause instanceof Error ? exit.error.cause.message : exit.error.message)
+      }
       const raw = list.map((item) => item.text).join("")
       const end = tail(raw, limits.maxLines, limits.maxBytes)
       if (end.cut) cut = true
@@ -585,8 +587,8 @@ export const ShellTool = Tool.define(
       return {
         title: input.command,
         metadata: {
-          output: last || preview(output),
-          exit: code,
+          output: exit.kind === "error" ? preview(output) : last || preview(output),
+          exit: exit.code,
           truncated: cut,
           ...(cut && file ? { outputPath: file } : {}),
         },
diff --git a/packages/opencode/test/cli/run/run-process.test.ts b/packages/opencode/test/cli/run/run-process.test.ts
index c6ccdc80cd41..fdb8ad5ed166 100644
--- a/packages/opencode/test/cli/run/run-process.test.ts
+++ b/packages/opencode/test/cli/run/run-process.test.ts
@@ -214,6 +214,43 @@ describe("opencode run (non-interactive subprocess)", () => {
     60_000,
   )
 
+  if (process.platform !== "win32") {
+    cliIt.live(
+      "--format json preserves signal termination output and continues",
+      ({ llm, opencode }) =>
+        Effect.gen(function* () {
+          yield* llm.push(
+            reply().tool("bash", {
+              command: "printf 'before-signal\\n'; kill -TERM $$",
+              description: "Terminate the tool shell with SIGTERM",
+              timeout: 10_000,
+            }),
+          )
+          yield* llm.text("continued after signal")
+
+          const result = yield* opencode.run("exercise signal termination", {
+            format: "json",
+            permission: { bash: "allow" },
+          })
+
+          opencode.expectExit(result, 0)
+          const events = opencode.parseJsonEvents(result.stdout)
+          expect(events.find((event) => event.type === "tool_use")?.part).toMatchObject({
+            tool: "bash",
+            state: {
+              status: "completed",
+              output: expect.stringMatching(/before-signal[\s\S]*SIGTERM/),
+              metadata: { exit: null, output: expect.stringContaining("SIGTERM") },
+            },
+          })
+          expect(result.stdout).toContain("continued after signal")
+          expect(result.stdout).not.toContain("ChildProcess.kill")
+          expect(result.stdout).not.toContain("exceeding timeout")
+        }),
+      60_000,
+    )
+  }
+
   cliIt.concurrent(
     "--format json records an unknown stream finish and continuation",
     ({ llm, opencode }) =>
diff --git a/packages/opencode/test/tool/shell.test.ts b/packages/opencode/test/tool/shell.test.ts
index 02c31ad81531..951de1ec88ee 100644
--- a/packages/opencode/test/tool/shell.test.ts
+++ b/packages/opencode/test/tool/shell.test.ts
@@ -1092,6 +1092,34 @@ describe("tool.shell abort", () => {
     )
   }
 
+  if (process.platform !== "win32") {
+    for (const signal of ["TERM", "SEGV", "KILL"]) {
+      it.live(`reports SIG${signal} without waiting for the command timeout`, () =>
+        runIn(
+          projectRoot,
+          Effect.gen(function* () {
+            const result = yield* run({
+              command: `ulimit -c 0; printf 'before-stdout\\n'; printf 'before-stderr\\n' >&2; kill -${signal} $$`,
+              timeout: 10_000,
+            }).pipe(
+              Effect.timeoutOrElse({
+                duration: "3 seconds",
+                orElse: () => Effect.die(new Error("Signal termination was not reported promptly")),
+              }),
+            )
+            expect(result.output).toContain("before-stdout")
+            expect(result.output).toContain("before-stderr")
+            expect(result.output).toContain(`SIG${signal}`)
+            expect(result.metadata.output).toBe(result.output)
+            expect(result.output).not.toContain("exceeding timeout")
+            expect(result.output).not.toContain("User aborted")
+            expect(result.metadata.exit).toBeNull()
+          }),
+        ),
+      )
+    }
+  }
+
   it.live("returns non-zero exit code", () =>
     runIn(
       projectRoot,