fix(opencode): preserve user request for skill slash commands

packages/opencode/src/command/index.ts

@@ -138,6 +138,9 @@ const layer = Layer.effect(
           name: item.name,
           description: item.description,
           source: "skill",
+          // Skill bodies are free-form markdown docs, not command templates.
+          // Placeholder substitution ($ARGUMENTS / $N) is applied by a fixed
+          // wrapper in SessionPrompt.command so docs cannot swallow user args.
           get template() {
             if (!dir) return item.content
             return [
@@ -147,7 +150,7 @@ const layer = Layer.effect(
               "Relative paths in this skill (e.g., scripts/, references/) are relative to this base directory.",
             ].join("\n")
           },
-          hints: [],
+          hints: ["$ARGUMENTS"],
         }
       }
 

packages/opencode/src/session/prompt.ts

@@ -1373,25 +1373,45 @@ const layer = Layer.effect(
       const args = raw.map((arg) => arg.replace(quoteTrimRegex, ""))
       const templateCommand = yield* Effect.promise(async () => cmd.template)
 
-      const placeholders = templateCommand.match(placeholderRegex) ?? []
-      let last = 0
-      for (const item of placeholders) {
-        const value = Number(item.slice(1))
-        if (value > last) last = value
-      }
+      let template: string
+      if (cmd.source === "skill") {
+        // Skills are free-form markdown, not command templates. Never run
+        // $ARGUMENTS / $N substitution against the skill body — docs often
+        // mention those tokens as examples and would swallow the real request.
+        // Keep the user request in a dedicated trailing section instead.
+        const request = input.arguments.trim()
+        template = [
+          `Follow the skill instructions below for skill "${cmd.name}".`,
+          "",
+          `<skill_content name="${cmd.name}">`,
+          templateCommand.trim(),
+          `</skill_content>`,
+          "",
+          "## User request",
+          request ||
+            "(No additional user request was provided. Follow the skill instructions and ask if anything is unclear.)",
+        ].join("\n")
+      } else {
+        const placeholders = templateCommand.match(placeholderRegex) ?? []
+        let last = 0
+        for (const item of placeholders) {
+          const value = Number(item.slice(1))
+          if (value > last) last = value
+        }
 
-      const withArgs = templateCommand.replaceAll(placeholderRegex, (_, index) => {
-        const position = Number(index)
-        const argIndex = position - 1
-        if (argIndex >= args.length) return ""
-        if (position === last) return args.slice(argIndex).join(" ")
-        return args[argIndex]
-      })
-      const usesArgumentsPlaceholder = templateCommand.includes("$ARGUMENTS")
-      let template = withArgs.replaceAll("$ARGUMENTS", input.arguments)
+        const withArgs = templateCommand.replaceAll(placeholderRegex, (_, index) => {
+          const position = Number(index)
+          const argIndex = position - 1
+          if (argIndex >= args.length) return ""
+          if (position === last) return args.slice(argIndex).join(" ")
+          return args[argIndex]
+        })
+        const usesArgumentsPlaceholder = templateCommand.includes("$ARGUMENTS")
+        template = withArgs.replaceAll("$ARGUMENTS", input.arguments)
 
-      if (placeholders.length === 0 && !usesArgumentsPlaceholder && input.arguments.trim()) {
-        template = template + "\n\n" + input.arguments
+        if (placeholders.length === 0 && !usesArgumentsPlaceholder && input.arguments.trim()) {
+          template = template + "\n\n" + input.arguments
+        }
       }
 
       const shellMatches = ConfigMarkdown.shell(template)

packages/opencode/test/session/prompt.test.ts

@@ -1776,6 +1776,56 @@ unix(
   30_000,
 )
 
+it.instance(
+  "skill slash command preserves user request and does not substitute skill body placeholders",
+  () =>
+    Effect.gen(function* () {
+      const { dir, llm } = yield* useServerConfig(providerCfg)
+      const skillDir = path.join(dir, ".opencode", "skill", "arg-skill")
+      yield* writeText(
+        path.join(skillDir, "SKILL.md"),
+        `---
+name: arg-skill
+description: Skill that documents $ARGUMENTS without consuming them.
+---
+
+# Arg Skill
+
+Example docs mention Input: $ARGUMENTS and also $1.
+
+Do the real work from the user request section only.
+`,
+      )
+
+      const { prompt, chat } = yield* boot()
+      yield* llm.text("done")
+
+      const result = yield* prompt.command({
+        sessionID: chat.id,
+        command: "arg-skill",
+        arguments: "please fix the login bug in src/auth.ts",
+      })
+
+      expect(result.info.role).toBe("assistant")
+      const sessions = yield* Session.Service
+      const messages = yield* sessions.messages({ sessionID: chat.id })
+      const user = messages.find((message) => message.info.role === "user")
+      const text = user?.parts
+        .filter((part) => part.type === "text")
+        .map((part) => part.text)
+        .join("\n")
+
+      expect(text).toContain('<skill_content name="arg-skill">')
+      expect(text).toContain("Example docs mention Input: $ARGUMENTS and also $1.")
+      expect(text).toContain("## User request")
+      expect(text).toContain("please fix the login bug in src/auth.ts")
+      // Placeholder tokens inside the skill body must remain literal.
+      expect(text).not.toMatch(/Example docs mention Input: please fix the login bug/)
+      expect(text).not.toMatch(/Example docs mention Input: please/)
+    }),
+  30_000,
+)
+
 unixNoLLMServer(
   "cancel interrupts shell and resolves cleanly",
   () =>