diff --git a/src/hooks/auto-slash-command/constants.test.ts b/src/hooks/auto-slash-command/constants.test.ts
new file mode 100644
index 000000000..6fd99647a
--- /dev/null
+++ b/src/hooks/auto-slash-command/constants.test.ts
@@ -0,0 +1,19 @@
+import { describe, expect, it } from "bun:test"
+import { parseSlashCommand } from "./detector"
+
+describe("slash command parsing pattern", () => {
+  describe("#given plugin namespace includes dot", () => {
+    it("#then parses command name with dot and colon", () => {
+      // given
+      const text = "/my.plugin:run ship"
+
+      // when
+      const parsed = parseSlashCommand(text)
+
+      // then
+      expect(parsed).not.toBeNull()
+      expect(parsed?.command).toBe("my.plugin:run")
+      expect(parsed?.args).toBe("ship")
+    })
+  })
+})
diff --git a/src/hooks/auto-slash-command/constants.ts b/src/hooks/auto-slash-command/constants.ts
index a8bdac19e..a5df43e9b 100644
--- a/src/hooks/auto-slash-command/constants.ts
+++ b/src/hooks/auto-slash-command/constants.ts
@@ -3,7 +3,7 @@ export const HOOK_NAME = "auto-slash-command" as const
 export const AUTO_SLASH_COMMAND_TAG_OPEN = "<auto-slash-command>"
 export const AUTO_SLASH_COMMAND_TAG_CLOSE = "</auto-slash-command>"
 
-export const SLASH_COMMAND_PATTERN = /^\/([a-zA-Z@][\w:@/-]*)\s*(.*)/
+export const SLASH_COMMAND_PATTERN = /^\/([a-zA-Z@][\w.:@/-]*)\s*(.*)/
 
 export const EXCLUDED_COMMANDS = new Set([
   "ralph-loop",
diff --git a/src/hooks/auto-slash-command/executor.test.ts b/src/hooks/auto-slash-command/executor.test.ts
index 979215fae..9f96e7a83 100644
--- a/src/hooks/auto-slash-command/executor.test.ts
+++ b/src/hooks/auto-slash-command/executor.test.ts
@@ -35,6 +35,14 @@ function writePluginFixture(baseDir: string): void {
 description: Run prompt from daplug
 ---
 Execute daplug prompt flow.
+`,
+  )
+  writeFileSync(
+    join(pluginInstallPath, "commands", "templated.md"),
+    `---
+description: Templated prompt from daplug
+---
+Echo $ARGUMENTS and \${user_message}.
 `,
   )
 
@@ -165,4 +173,23 @@ describe("auto-slash command executor plugin dispatch", () => {
     )
     expect(result.error).not.toContain("Marketplace plugin commands")
   })
+
+  it("replaces $ARGUMENTS placeholders in plugin command templates", async () => {
+    const result = await executeSlashCommand(
+      {
+        command: "daplug:templated",
+        args: "ship it",
+        raw: "/daplug:templated ship it",
+      },
+      {
+        skills: [],
+        pluginsEnabled: true,
+      },
+    )
+
+    expect(result.success).toBe(true)
+    expect(result.replacementText).toContain("Echo ship it and ship it.")
+    expect(result.replacementText).not.toContain("$ARGUMENTS")
+    expect(result.replacementText).not.toContain("${user_message}")
+  })
 })
diff --git a/src/hooks/auto-slash-command/executor.ts b/src/hooks/auto-slash-command/executor.ts
index f7c906e20..cd06ee78d 100644
--- a/src/hooks/auto-slash-command/executor.ts
+++ b/src/hooks/auto-slash-command/executor.ts
@@ -7,16 +7,12 @@ import {
   sanitizeModelField,
   getClaudeConfigDir,
   getOpenCodeConfigDir,
+  discoverPluginCommandDefinitions,
 } from "../../shared"
 import { loadBuiltinCommands } from "../../features/builtin-commands"
 import type { CommandFrontmatter } from "../../features/claude-code-command-loader/types"
 import { isMarkdownFile } from "../../shared/file-utils"
 import { discoverAllSkills, type LoadedSkill, type LazyContentLoader } from "../../features/opencode-skill-loader"
-import {
-  discoverInstalledPlugins,
-  loadPluginCommands,
-  loadPluginSkillsAsCommands,
-} from "../../features/claude-code-plugin-loader"
 import type { ParsedSlashCommand } from "./types"
 
 interface CommandScope {
@@ -109,18 +105,7 @@ export interface ExecutorOptions {
 }
 
 function discoverPluginCommands(options?: ExecutorOptions): CommandInfo[] {
-  if (options?.pluginsEnabled === false) {
-    return []
-  }
-
-  const { plugins } = discoverInstalledPlugins({
-    enabledPluginsOverride: options?.enabledPluginsOverride,
-  })
-
-  const pluginDefinitions = {
-    ...loadPluginCommands(plugins),
-    ...loadPluginSkillsAsCommands(plugins),
-  }
+  const pluginDefinitions = discoverPluginCommandDefinitions(options)
 
   return Object.entries(pluginDefinitions).map(([name, definition]) => ({
     name,
@@ -216,7 +201,11 @@ async function formatCommandTemplate(cmd: CommandInfo, args: string): Promise<st
   const commandDir = cmd.path ? dirname(cmd.path) : process.cwd()
   const withFileRefs = await resolveFileReferencesInText(content, commandDir)
   const resolvedContent = await resolveCommandsInText(withFileRefs)
-  sections.push(resolvedContent.trim())
+  const resolvedArguments = args
+  const substitutedContent = resolvedContent
+    .replace(/\$\{user_message\}/g, resolvedArguments)
+    .replace(/\$ARGUMENTS/g, resolvedArguments)
+  sections.push(substitutedContent.trim())
 
   if (args) {
     sections.push("\n\n---\n")
diff --git a/src/shared/index.ts b/src/shared/index.ts
index 8615a7750..39b36482a 100644
--- a/src/shared/index.ts
+++ b/src/shared/index.ts
@@ -60,4 +60,5 @@ export * from "./normalize-sdk-response"
 export * from "./session-directory-resolver"
 export * from "./prompt-tools"
 export * from "./internal-initiator-marker"
+export * from "./plugin-command-discovery"
 export { SessionCategoryRegistry } from "./session-category-registry"
diff --git a/src/shared/plugin-command-discovery.test.ts b/src/shared/plugin-command-discovery.test.ts
new file mode 100644
index 000000000..0d45bdc8b
--- /dev/null
+++ b/src/shared/plugin-command-discovery.test.ts
@@ -0,0 +1,135 @@
+import { afterEach, beforeEach, describe, expect, it } from "bun:test"
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import { discoverPluginCommandDefinitions } from "./plugin-command-discovery"
+
+const ENV_KEYS = [
+  "CLAUDE_CONFIG_DIR",
+  "CLAUDE_PLUGINS_HOME",
+  "CLAUDE_SETTINGS_PATH",
+  "OPENCODE_CONFIG_DIR",
+] as const
+
+type EnvKey = (typeof ENV_KEYS)[number]
+type EnvSnapshot = Record<EnvKey, string | undefined>
+
+function writePluginFixture(baseDir: string): void {
+  const claudeConfigDir = join(baseDir, "claude-config")
+  const pluginsHome = join(claudeConfigDir, "plugins")
+  const settingsPath = join(claudeConfigDir, "settings.json")
+  const opencodeConfigDir = join(baseDir, "opencode-config")
+  const pluginInstallPath = join(baseDir, "installed-plugins", "daplug")
+  const pluginKey = "daplug@1.0.0"
+
+  mkdirSync(join(pluginInstallPath, ".claude-plugin"), { recursive: true })
+  mkdirSync(join(pluginInstallPath, "commands"), { recursive: true })
+  mkdirSync(join(pluginInstallPath, "skills", "plugin-plan"), { recursive: true })
+
+  writeFileSync(
+    join(pluginInstallPath, ".claude-plugin", "plugin.json"),
+    JSON.stringify({ name: "daplug", version: "1.0.0" }, null, 2),
+  )
+  writeFileSync(
+    join(pluginInstallPath, "commands", "run-prompt.md"),
+    `---
+description: Run prompt from daplug
+---
+Execute daplug prompt flow.
+`,
+  )
+  writeFileSync(
+    join(pluginInstallPath, "skills", "plugin-plan", "SKILL.md"),
+    `---
+name: plugin-plan
+description: Plan work from daplug skill
+---
+Build a plan from plugin skill context.
+`,
+  )
+
+  mkdirSync(pluginsHome, { recursive: true })
+  writeFileSync(
+    join(pluginsHome, "installed_plugins.json"),
+    JSON.stringify(
+      {
+        version: 2,
+        plugins: {
+          [pluginKey]: [
+            {
+              scope: "user",
+              installPath: pluginInstallPath,
+              version: "1.0.0",
+              installedAt: "2026-01-01T00:00:00.000Z",
+              lastUpdated: "2026-01-01T00:00:00.000Z",
+            },
+          ],
+        },
+      },
+      null,
+      2,
+    ),
+  )
+
+  mkdirSync(claudeConfigDir, { recursive: true })
+  writeFileSync(
+    settingsPath,
+    JSON.stringify(
+      {
+        enabledPlugins: {
+          [pluginKey]: true,
+        },
+      },
+      null,
+      2,
+    ),
+  )
+  mkdirSync(opencodeConfigDir, { recursive: true })
+
+  process.env.CLAUDE_CONFIG_DIR = claudeConfigDir
+  process.env.CLAUDE_PLUGINS_HOME = pluginsHome
+  process.env.CLAUDE_SETTINGS_PATH = settingsPath
+  process.env.OPENCODE_CONFIG_DIR = opencodeConfigDir
+}
+
+describe("plugin command discovery utility", () => {
+  let tempDir = ""
+  let envSnapshot: EnvSnapshot
+
+  beforeEach(() => {
+    tempDir = mkdtempSync(join(tmpdir(), "omo-shared-plugin-discovery-test-"))
+    envSnapshot = {
+      CLAUDE_CONFIG_DIR: process.env.CLAUDE_CONFIG_DIR,
+      CLAUDE_PLUGINS_HOME: process.env.CLAUDE_PLUGINS_HOME,
+      CLAUDE_SETTINGS_PATH: process.env.CLAUDE_SETTINGS_PATH,
+      OPENCODE_CONFIG_DIR: process.env.OPENCODE_CONFIG_DIR,
+    }
+    writePluginFixture(tempDir)
+  })
+
+  afterEach(() => {
+    for (const key of ENV_KEYS) {
+      const previousValue = envSnapshot[key]
+      if (previousValue === undefined) {
+        delete process.env[key]
+      } else {
+        process.env[key] = previousValue
+      }
+    }
+    rmSync(tempDir, { recursive: true, force: true })
+  })
+
+  describe("#given plugin loading is enabled", () => {
+    it("#then returns plugin command and skill definitions", () => {
+      // given
+      const options = { pluginsEnabled: true }
+
+      // when
+      const definitions = discoverPluginCommandDefinitions(options)
+
+      // then
+      expect(Object.keys(definitions)).toContain("daplug:run-prompt")
+      expect(Object.keys(definitions)).toContain("daplug:plugin-plan")
+    })
+  })
+})
diff --git a/src/shared/plugin-command-discovery.ts b/src/shared/plugin-command-discovery.ts
new file mode 100644
index 000000000..615bf0b52
--- /dev/null
+++ b/src/shared/plugin-command-discovery.ts
@@ -0,0 +1,28 @@
+import {
+  discoverInstalledPlugins,
+  loadPluginCommands,
+  loadPluginSkillsAsCommands,
+} from "../features/claude-code-plugin-loader"
+import type { CommandDefinition } from "../features/claude-code-command-loader/types"
+
+export interface PluginCommandDiscoveryOptions {
+  pluginsEnabled?: boolean
+  enabledPluginsOverride?: Record<string, boolean>
+}
+
+export function discoverPluginCommandDefinitions(
+  options?: PluginCommandDiscoveryOptions,
+): Record<string, CommandDefinition> {
+  if (options?.pluginsEnabled === false) {
+    return {}
+  }
+
+  const { plugins } = discoverInstalledPlugins({
+    enabledPluginsOverride: options?.enabledPluginsOverride,
+  })
+
+  return {
+    ...loadPluginCommands(plugins),
+    ...loadPluginSkillsAsCommands(plugins),
+  }
+}
diff --git a/src/tools/slashcommand/command-discovery.ts b/src/tools/slashcommand/command-discovery.ts
index 57182f020..078380526 100644
--- a/src/tools/slashcommand/command-discovery.ts
+++ b/src/tools/slashcommand/command-discovery.ts
@@ -1,15 +1,15 @@
 import { existsSync, readdirSync, readFileSync } from "fs"
 import { basename, join } from "path"
-import { parseFrontmatter, sanitizeModelField, getOpenCodeConfigDir } from "../../shared"
+import {
+  parseFrontmatter,
+  sanitizeModelField,
+  getOpenCodeConfigDir,
+  discoverPluginCommandDefinitions,
+} from "../../shared"
 import type { CommandFrontmatter } from "../../features/claude-code-command-loader/types"
 import { isMarkdownFile } from "../../shared/file-utils"
 import { getClaudeConfigDir } from "../../shared"
 import { loadBuiltinCommands } from "../../features/builtin-commands"
-import {
-  discoverInstalledPlugins,
-  loadPluginCommands,
-  loadPluginSkillsAsCommands,
-} from "../../features/claude-code-plugin-loader"
 import type { CommandInfo, CommandMetadata, CommandScope } from "./types"
 
 export interface CommandDiscoveryOptions {
@@ -59,18 +59,7 @@ function discoverCommandsFromDir(commandsDir: string, scope: CommandScope): Comm
 }
 
 function discoverPluginCommands(options?: CommandDiscoveryOptions): CommandInfo[] {
-  if (options?.pluginsEnabled === false) {
-    return []
-  }
-
-  const { plugins } = discoverInstalledPlugins({
-    enabledPluginsOverride: options?.enabledPluginsOverride,
-  })
-
-  const pluginDefinitions = {
-    ...loadPluginCommands(plugins),
-    ...loadPluginSkillsAsCommands(plugins),
-  }
+  const pluginDefinitions = discoverPluginCommandDefinitions(options)
 
   return Object.entries(pluginDefinitions).map(([name, definition]) => ({
     name,
diff --git a/src/tools/slashcommand/command-output-formatter.test.ts b/src/tools/slashcommand/command-output-formatter.test.ts
new file mode 100644
index 000000000..dd2b7c169
--- /dev/null
+++ b/src/tools/slashcommand/command-output-formatter.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, it } from "bun:test"
+import { formatLoadedCommand } from "./command-output-formatter"
+import type { CommandInfo } from "./types"
+
+describe("command output formatter", () => {
+  describe("#given command template includes argument placeholders", () => {
+    it("#then replaces both placeholder forms", async () => {
+      // given
+      const command: CommandInfo = {
+        name: "daplug:templated",
+        metadata: {
+          name: "daplug:templated",
+          description: "Templated plugin command",
+        },
+        content: "Echo $ARGUMENTS and ${user_message}.",
+        scope: "plugin",
+      }
+
+      // when
+      const output = await formatLoadedCommand(command, "ship it")
+
+      // then
+      expect(output).toContain("Echo ship it and ship it.")
+      expect(output).not.toContain("$ARGUMENTS")
+      expect(output).not.toContain("${user_message}")
+    })
+  })
+})
diff --git a/src/tools/slashcommand/command-output-formatter.ts b/src/tools/slashcommand/command-output-formatter.ts
index 36c714c68..cbfe8a417 100644
--- a/src/tools/slashcommand/command-output-formatter.ts
+++ b/src/tools/slashcommand/command-output-formatter.ts
@@ -49,7 +49,9 @@ export async function formatLoadedCommand(
 
   let finalContent = resolvedContent.trim()
   if (userMessage) {
-    finalContent = finalContent.replace(/\$\{user_message\}/g, userMessage)
+    finalContent = finalContent
+      .replace(/\$\{user_message\}/g, userMessage)
+      .replace(/\$ARGUMENTS/g, userMessage)
   }
 
   sections.push(finalContent)