diff --git a/CHANGELOG.md b/CHANGELOG.md
index 052510b8628..ebbfb3f0924 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -62,6 +62,7 @@ Docs: https://docs.openclaw.ai
 - CLI/startup: lazy-load channel add and root help startup paths to trim avoidable RSS and help latency on constrained hosts. (#46784) Thanks @vincentkoc.
 - CLI/onboarding: import static provider definitions directly for onboarding model/config helpers so those paths no longer pull provider discovery just for built-in defaults. (#47467) Thanks @vincentkoc.
 - CLI/auth choice: lazy-load plugin/provider fallback resolution so mapped auth choices stay on the static path and only unknown choices pay the heavy provider load. (#47495) Thanks @vincentkoc.
+- CLI/completion: reduce recursive completion-script string churn and fix nested PowerShell command-path matching so generated nested completions resolve on PowerShell too. (#45537) Thanks @yiShanXin and @vincentkoc.
 
 ## 2026.3.13
 
diff --git a/src/cli/completion-cli.test.ts b/src/cli/completion-cli.test.ts
new file mode 100644
index 00000000000..d2f34b0e8cb
--- /dev/null
+++ b/src/cli/completion-cli.test.ts
@@ -0,0 +1,52 @@
+import { Command } from "commander";
+import { describe, expect, it } from "vitest";
+import { getCompletionScript } from "./completion-cli.js";
+
+function createCompletionProgram(): Command {
+  const program = new Command();
+  program.name("openclaw");
+  program.description("CLI root");
+  program.option("-v, --verbose", "Verbose output");
+
+  const gateway = program.command("gateway").description("Gateway commands");
+  gateway.option("--force", "Force the action");
+
+  gateway.command("status").description("Show gateway status").option("--json", "JSON output");
+  gateway.command("restart").description("Restart gateway");
+
+  return program;
+}
+
+describe("completion-cli", () => {
+  it("generates zsh functions for nested subcommands", () => {
+    const script = getCompletionScript("zsh", createCompletionProgram());
+
+    expect(script).toContain("_openclaw_gateway()");
+    expect(script).toContain("(status) _openclaw_gateway_status ;;");
+    expect(script).toContain("(restart) _openclaw_gateway_restart ;;");
+    expect(script).toContain("--force[Force the action]");
+  });
+
+  it("generates PowerShell command paths without the executable prefix", () => {
+    const script = getCompletionScript("powershell", createCompletionProgram());
+
+    expect(script).toContain("if ($commandPath -eq 'gateway') {");
+    expect(script).toContain("if ($commandPath -eq 'gateway status') {");
+    expect(script).not.toContain("if ($commandPath -eq 'openclaw gateway') {");
+    expect(script).toContain("$completions = @('status','restart','--force')");
+  });
+
+  it("generates fish completions for root and nested command contexts", () => {
+    const script = getCompletionScript("fish", createCompletionProgram());
+
+    expect(script).toContain(
+      'complete -c openclaw -n "__fish_use_subcommand" -a "gateway" -d \'Gateway commands\'',
+    );
+    expect(script).toContain(
+      'complete -c openclaw -n "__fish_seen_subcommand_from gateway" -a "status" -d \'Show gateway status\'',
+    );
+    expect(script).toContain(
+      "complete -c openclaw -n \"__fish_seen_subcommand_from gateway\" -l force -d 'Force the action'",
+    );
+  });
+});
diff --git a/src/cli/completion-cli.ts b/src/cli/completion-cli.ts
index 01cd02c018c..cbc235e41f9 100644
--- a/src/cli/completion-cli.ts
+++ b/src/cli/completion-cli.ts
@@ -69,7 +69,7 @@ export async function completionCacheExists(
   return pathExists(cachePath);
 }
 
-function getCompletionScript(shell: CompletionShell, program: Command): string {
+export function getCompletionScript(shell: CompletionShell, program: Command): string {
   if (shell === "zsh") {
     return generateZshCompletion(program);
   }
@@ -442,17 +442,19 @@ function generateZshSubcmdList(cmd: Command): string {
 }
 
 function generateZshSubcommands(program: Command, prefix: string): string {
-  let script = "";
-  for (const cmd of program.commands) {
-    const cmdName = cmd.name();
-    const funcName = `_${prefix}_${cmdName.replace(/-/g, "_")}`;
+  const segments: string[] = [];
 
-    // Recurse first
-    script += generateZshSubcommands(cmd, `${prefix}_${cmdName.replace(/-/g, "_")}`);
+  const visit = (current: Command, currentPrefix: string) => {
+    for (const cmd of current.commands) {
+      const cmdName = cmd.name();
+      const nextPrefix = `${currentPrefix}_${cmdName.replace(/-/g, "_")}`;
+      const funcName = `_${nextPrefix}`;
 
-    const subCommands = cmd.commands;
-    if (subCommands.length > 0) {
-      script += `
+      visit(cmd, nextPrefix);
+
+      const subCommands = cmd.commands;
+      if (subCommands.length > 0) {
+        segments.push(`
 ${funcName}() {
   local -a commands
   local -a options
@@ -470,17 +472,21 @@ ${funcName}() {
       ;;
   esac
 }
-`;
-    } else {
-      script += `
+`);
+        continue;
+      }
+
+      segments.push(`
 ${funcName}() {
   _arguments -C \\
     ${generateZshArgs(cmd)}
 }
-`;
+`);
     }
-  }
-  return script;
+  };
+
+  visit(program, prefix);
+  return segments.join("");
 }
 
 function generateBashCompletion(program: Command): string {
@@ -528,38 +534,34 @@ function generateBashSubcommand(cmd: Command): string {
 
 function generatePowerShellCompletion(program: Command): string {
   const rootCmd = program.name();
+  const segments: string[] = [];
 
-  const visit = (cmd: Command, parents: string[]): string => {
-    const cmdName = cmd.name();
-    const fullPath = [...parents, cmdName].join(" ");
-
-    let script = "";
+  const visit = (cmd: Command, pathSegments: string[]) => {
+    const fullPath = pathSegments.join(" ");
 
     // Command completion for this level
     const subCommands = cmd.commands.map((c) => c.name());
     const options = cmd.options.map((o) => o.flags.split(/[ ,|]+/)[0]); // Take first flag
     const allCompletions = [...subCommands, ...options].map((s) => `'${s}'`).join(",");
 
-    if (allCompletions.length > 0) {
-      script += `
+    if (fullPath.length > 0 && allCompletions.length > 0) {
+      segments.push(`
             if ($commandPath -eq '${fullPath}') {
                 $completions = @(${allCompletions})
                 $completions | Where-Object { $_ -like "$wordToComplete*" } | ForEach-Object {
                     [System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterName', $_)
                 }
             }
-`;
+`);
     }
 
-    // Recurse
     for (const sub of cmd.commands) {
-      script += visit(sub, [...parents, cmdName]);
+      visit(sub, [...pathSegments, sub.name()]);
     }
-
-    return script;
   };
 
-  const rootBody = visit(program, []);
+  visit(program, []);
+  const rootBody = segments.join("");
 
   return `
 Register-ArgumentCompleter -Native -CommandName ${rootCmd} -ScriptBlock {
@@ -593,65 +595,57 @@ Register-ArgumentCompleter -Native -CommandName ${rootCmd} -ScriptBlock {
 
 function generateFishCompletion(program: Command): string {
   const rootCmd = program.name();
-  let script = "";
+  const segments: string[] = [];
 
   const visit = (cmd: Command, parents: string[]) => {
     const cmdName = cmd.name();
-    const fullPath = [...parents];
-    if (parents.length > 0) {
-      fullPath.push(cmdName);
-    } // Only push if not root, or consistent root handling
-
-    // Fish uses 'seen_subcommand_from' to determine context.
-    // For root: complete -c openclaw -n "__fish_use_subcommand" -a "subcmd" -d "desc"
 
     // Root logic
     if (parents.length === 0) {
       // Subcommands of root
       for (const sub of cmd.commands) {
-        script += buildFishSubcommandCompletionLine({
-          rootCmd,
-          condition: "__fish_use_subcommand",
-          name: sub.name(),
-          description: sub.description(),
-        });
+        segments.push(
+          buildFishSubcommandCompletionLine({
+            rootCmd,
+            condition: "__fish_use_subcommand",
+            name: sub.name(),
+            description: sub.description(),
+          }),
+        );
       }
       // Options of root
       for (const opt of cmd.options) {
-        script += buildFishOptionCompletionLine({
-          rootCmd,
-          condition: "__fish_use_subcommand",
-          flags: opt.flags,
-          description: opt.description,
-        });
+        segments.push(
+          buildFishOptionCompletionLine({
+            rootCmd,
+            condition: "__fish_use_subcommand",
+            flags: opt.flags,
+            description: opt.description,
+          }),
+        );
       }
     } else {
-      // Nested commands
-      // Logic: if seen subcommand matches parents...
-      // But fish completion logic is simpler if we just say "if we haven't seen THIS command yet but seen parent"
-      // Actually, a robust fish completion often requires defining a function to check current line.
-      // For simplicity, we'll assume standard fish helper __fish_seen_subcommand_from.
-
-      // To properly scope to 'openclaw gateway' and not 'openclaw other gateway', we need to check the sequence.
-      // A simplified approach:
-
       // Subcommands
       for (const sub of cmd.commands) {
-        script += buildFishSubcommandCompletionLine({
-          rootCmd,
-          condition: `__fish_seen_subcommand_from ${cmdName}`,
-          name: sub.name(),
-          description: sub.description(),
-        });
+        segments.push(
+          buildFishSubcommandCompletionLine({
+            rootCmd,
+            condition: `__fish_seen_subcommand_from ${cmdName}`,
+            name: sub.name(),
+            description: sub.description(),
+          }),
+        );
       }
       // Options
       for (const opt of cmd.options) {
-        script += buildFishOptionCompletionLine({
-          rootCmd,
-          condition: `__fish_seen_subcommand_from ${cmdName}`,
-          flags: opt.flags,
-          description: opt.description,
-        });
+        segments.push(
+          buildFishOptionCompletionLine({
+            rootCmd,
+            condition: `__fish_seen_subcommand_from ${cmdName}`,
+            flags: opt.flags,
+            description: opt.description,
+          }),
+        );
       }
     }
 
@@ -661,5 +655,5 @@ function generateFishCompletion(program: Command): string {
   };
 
   visit(program, []);
-  return script;
+  return segments.join("");
 }
diff --git a/src/plugins/loader.test.ts b/src/plugins/loader.test.ts
index c37cfbfd46c..ac6ff410268 100644
--- a/src/plugins/loader.test.ts
+++ b/src/plugins/loader.test.ts
@@ -986,6 +986,153 @@ describe("loadOpenClawPlugins", () => {
     expect(httpPlugin?.httpRoutes).toBe(1);
   });
 
+  it("rejects duplicate plugin-visible hook names", () => {
+    useNoBundledPlugins();
+    const first = writePlugin({
+      id: "hook-owner-a",
+      filename: "hook-owner-a.cjs",
+      body: `module.exports = { id: "hook-owner-a", register(api) {
+  api.registerHook("gateway:startup", () => {}, { name: "shared-hook" });
+} };`,
+    });
+    const second = writePlugin({
+      id: "hook-owner-b",
+      filename: "hook-owner-b.cjs",
+      body: `module.exports = { id: "hook-owner-b", register(api) {
+  api.registerHook("gateway:startup", () => {}, { name: "shared-hook" });
+} };`,
+    });
+
+    const registry = loadOpenClawPlugins({
+      cache: false,
+      config: {
+        plugins: {
+          load: { paths: [first.file, second.file] },
+          allow: ["hook-owner-a", "hook-owner-b"],
+        },
+      },
+    });
+
+    expect(registry.hooks.filter((entry) => entry.entry.hook.name === "shared-hook")).toHaveLength(
+      1,
+    );
+    expect(
+      registry.diagnostics.some(
+        (diag) =>
+          diag.level === "error" &&
+          diag.pluginId === "hook-owner-b" &&
+          diag.message === "hook already registered: shared-hook (hook-owner-a)",
+      ),
+    ).toBe(true);
+  });
+
+  it("rejects duplicate plugin service ids", () => {
+    useNoBundledPlugins();
+    const first = writePlugin({
+      id: "service-owner-a",
+      filename: "service-owner-a.cjs",
+      body: `module.exports = { id: "service-owner-a", register(api) {
+  api.registerService({ id: "shared-service", start() {} });
+} };`,
+    });
+    const second = writePlugin({
+      id: "service-owner-b",
+      filename: "service-owner-b.cjs",
+      body: `module.exports = { id: "service-owner-b", register(api) {
+  api.registerService({ id: "shared-service", start() {} });
+} };`,
+    });
+
+    const registry = loadOpenClawPlugins({
+      cache: false,
+      config: {
+        plugins: {
+          load: { paths: [first.file, second.file] },
+          allow: ["service-owner-a", "service-owner-b"],
+        },
+      },
+    });
+
+    expect(registry.services.filter((entry) => entry.service.id === "shared-service")).toHaveLength(
+      1,
+    );
+    expect(
+      registry.diagnostics.some(
+        (diag) =>
+          diag.level === "error" &&
+          diag.pluginId === "service-owner-b" &&
+          diag.message === "service already registered: shared-service (service-owner-a)",
+      ),
+    ).toBe(true);
+  });
+
+  it("requires plugin CLI registrars to declare explicit command roots", () => {
+    useNoBundledPlugins();
+    const plugin = writePlugin({
+      id: "cli-missing-metadata",
+      filename: "cli-missing-metadata.cjs",
+      body: `module.exports = { id: "cli-missing-metadata", register(api) {
+  api.registerCli(() => {});
+} };`,
+    });
+
+    const registry = loadRegistryFromSinglePlugin({
+      plugin,
+      pluginConfig: {
+        allow: ["cli-missing-metadata"],
+      },
+    });
+
+    expect(registry.cliRegistrars).toHaveLength(0);
+    expect(
+      registry.diagnostics.some(
+        (diag) =>
+          diag.level === "error" &&
+          diag.pluginId === "cli-missing-metadata" &&
+          diag.message === "cli registration missing explicit commands metadata",
+      ),
+    ).toBe(true);
+  });
+
+  it("rejects duplicate plugin CLI command roots", () => {
+    useNoBundledPlugins();
+    const first = writePlugin({
+      id: "cli-owner-a",
+      filename: "cli-owner-a.cjs",
+      body: `module.exports = { id: "cli-owner-a", register(api) {
+  api.registerCli(() => {}, { commands: ["shared-cli"] });
+} };`,
+    });
+    const second = writePlugin({
+      id: "cli-owner-b",
+      filename: "cli-owner-b.cjs",
+      body: `module.exports = { id: "cli-owner-b", register(api) {
+  api.registerCli(() => {}, { commands: ["shared-cli"] });
+} };`,
+    });
+
+    const registry = loadOpenClawPlugins({
+      cache: false,
+      config: {
+        plugins: {
+          load: { paths: [first.file, second.file] },
+          allow: ["cli-owner-a", "cli-owner-b"],
+        },
+      },
+    });
+
+    expect(registry.cliRegistrars).toHaveLength(1);
+    expect(registry.cliRegistrars[0]?.pluginId).toBe("cli-owner-a");
+    expect(
+      registry.diagnostics.some(
+        (diag) =>
+          diag.level === "error" &&
+          diag.pluginId === "cli-owner-b" &&
+          diag.message === "cli command already registered: shared-cli (cli-owner-a)",
+      ),
+    ).toBe(true);
+  });
+
   it("registers http routes", () => {
     useNoBundledPlugins();
     const plugin = writePlugin({
diff --git a/src/plugins/registry.ts b/src/plugins/registry.ts
index ca987dc8e79..c1c63cc96cb 100644
--- a/src/plugins/registry.ts
+++ b/src/plugins/registry.ts
@@ -238,6 +238,16 @@ export function createPluginRegistry(registryParams: PluginRegistryParams) {
       });
       return;
     }
+    const existingHook = registry.hooks.find((entry) => entry.entry.hook.name === name);
+    if (existingHook) {
+      pushDiagnostic({
+        level: "error",
+        pluginId: record.id,
+        source: record.source,
+        message: `hook already registered: ${name} (${existingHook.pluginId})`,
+      });
+      return;
+    }
 
     const description = entry?.hook.description ?? opts?.description ?? "";
     const hookEntry: HookEntry = entry
@@ -473,6 +483,28 @@ export function createPluginRegistry(registryParams: PluginRegistryParams) {
     opts?: { commands?: string[] },
   ) => {
     const commands = (opts?.commands ?? []).map((cmd) => cmd.trim()).filter(Boolean);
+    if (commands.length === 0) {
+      pushDiagnostic({
+        level: "error",
+        pluginId: record.id,
+        source: record.source,
+        message: "cli registration missing explicit commands metadata",
+      });
+      return;
+    }
+    const existing = registry.cliRegistrars.find((entry) =>
+      entry.commands.some((command) => commands.includes(command)),
+    );
+    if (existing) {
+      const overlap = commands.find((command) => existing.commands.includes(command));
+      pushDiagnostic({
+        level: "error",
+        pluginId: record.id,
+        source: record.source,
+        message: `cli command already registered: ${overlap ?? commands[0]} (${existing.pluginId})`,
+      });
+      return;
+    }
     record.cliCommands.push(...commands);
     registry.cliRegistrars.push({
       pluginId: record.id,
@@ -487,6 +519,16 @@ export function createPluginRegistry(registryParams: PluginRegistryParams) {
     if (!id) {
       return;
     }
+    const existing = registry.services.find((entry) => entry.service.id === id);
+    if (existing) {
+      pushDiagnostic({
+        level: "error",
+        pluginId: record.id,
+        source: record.source,
+        message: `service already registered: ${id} (${existing.pluginId})`,
+      });
+      return;
+    }
     record.services.push(id);
     registry.services.push({
       pluginId: record.id,