diff --git a/packages/opencode/src/session/system.ts b/packages/opencode/src/session/system.ts
index 06c71fa7dbdd..e5dad5401c85 100644
--- a/packages/opencode/src/session/system.ts
+++ b/packages/opencode/src/session/system.ts
@@ -58,6 +58,12 @@ export const layer = Layer.effect(
             `  Platform: ${process.platform}`,
             `  Today's date: ${new Date().toDateString()}`,
             `</env>`,
+            ``,
+            `## System Safety (Critical)`,
+            ``,
+            `- **NEVER** run commands that kill all Node.js processes (e.g., \`taskkill /F /IM node.exe\`, \`killall node\`, \`pkill node\`, \`Get-Process node | Stop-Process\`, etc.).`,
+            `- OpenCode is built on Node.js (\`node.exe\`). Killing all Node processes will immediately crash the AI assistant and terminate the current session.`,
+            `- If you need to stop a specific process, target it by PID or use process-manager commands scoped to the project (e.g., \`npm stop\`, \`pm2 stop <name>\`).`,
           ].join("\n"),
         ]
       }),
diff --git a/packages/opencode/src/tool/shell.ts b/packages/opencode/src/tool/shell.ts
index d3ca542684de..46c56ed858a4 100644
--- a/packages/opencode/src/tool/shell.ts
+++ b/packages/opencode/src/tool/shell.ts
@@ -28,6 +28,18 @@ export { Parameters } from "./shell/prompt"
 const MAX_METADATA_LENGTH = 30_000
 const DEFAULT_TIMEOUT = Flag.OPENCODE_EXPERIMENTAL_BASH_DEFAULT_TIMEOUT_MS || 2 * 60 * 1000
 const CWD = new Set(["cd", "chdir", "popd", "pushd", "push-location", "set-location"])
+
+const DANGEROUS_COMMAND_PATTERNS = [
+  /taskkill\s+.*\/?[Ff]\s+.*\/?[Ii][Mm]\s+node\.?exe/i,
+  /taskkill\s+.*\/?[Ii][Mm]\s+node\.?exe/i,
+  /killall\s+node/i,
+  /pkill\s+node/i,
+  /Get-Process\s+.*node\s*\|\s*Stop-Process/i,
+]
+
+function isDangerousCommand(command: string): boolean {
+  return DANGEROUS_COMMAND_PATTERNS.some((pattern) => pattern.test(command))
+}
 const FILES = new Set([
   ...CWD,
   "rm",
@@ -601,6 +613,11 @@ export const ShellTool = Tool.define(
                 throw new Error(`Invalid timeout value: ${params.timeout}. Timeout must be a positive number.`)
               }
               const timeout = params.timeout ?? DEFAULT_TIMEOUT
+              if (isDangerousCommand(params.command)) {
+                throw new Error(
+                  `Command blocked for system safety: "${params.command}". This command would kill all Node.js processes, which crashes OpenCode because it is built on Node.js (node.exe). If you need to stop a specific process, target it by PID or use project-scoped commands like "npm stop" or "pm2 stop <name>".`,
+                )
+              }
               const ps = Shell.ps(shell)
               yield* Effect.scoped(
                 Effect.gen(function* () {
diff --git a/packages/opencode/src/tool/shell/shell.txt b/packages/opencode/src/tool/shell/shell.txt
index 5cba07805c1e..ca9837efdf43 100644
--- a/packages/opencode/src/tool/shell/shell.txt
+++ b/packages/opencode/src/tool/shell/shell.txt
@@ -8,6 +8,12 @@ Use `${tmp}` for temporary work outside the workspace. This directory has alread
 
 IMPORTANT: This tool is for terminal operations like git, npm, docker, etc. DO NOT use it for file operations (reading, writing, editing, searching, finding files) - use the specialized tools for this instead.
 
+## System Safety (Critical)
+
+- **NEVER** run commands that kill all Node.js processes (e.g., `taskkill /F /IM node.exe`, `killall node`, `pkill node`, `Get-Process node | Stop-Process`, etc.).
+- OpenCode is built on Node.js (`node.exe`). Killing all Node processes will immediately crash the AI assistant and terminate the current session.
+- If you need to stop a specific process, target it by PID or use process-manager commands scoped to the project (e.g., `npm stop`, `pm2 stop <name>`).
+
 ${commandSection}
 
 # Committing changes with git