Explicit slash skill is redundantly reloaded through model registry and fails with “Skill not found”

Describe the bug

An explicitly invoked interactive slash skill is successfully resolved and expanded into the conversation, but the assistant then attempts to load the same skill through the model-facing skill() tool. For skills excluded from model invocation, that redundant call fails with Skill not found, and the requested workflow does not start.

This differs from #4438: the interactive /skill resolver succeeds and provides the skill context. The failure happens afterward because the assistant routes the already-resolved explicit invocation back through the model-only registry.

Affected version

GitHub Copilot CLI 1.0.79

Steps to reproduce the behavior

1. Create a personal skill at %USERPROFILE%\.agents\skills\implement.

2. Configure agents\openai.yaml:

   interface:
     display_name: "Implement"
     short_description: "Build work from a spec or tickets"
   policy:
     allow_implicit_invocation: false
   

3. Start an interactive Copilot CLI session using GPT-5.6 Sol.

4. Invoke the skill directly:

   /implement 5514365
   

5. The CLI successfully injects an explicit invocation message and <skill-context name="implement"> containing the skill's base directory and instructions.

6. Instead of following that supplied context, the assistant calls the model-facing tool:

   skill: "implement"
   

7. The tool returns:

   Skill not found: implement
   

The same session shows that skills with allow_implicit_invocation: false are absent from the model-facing registry, while skills without that policy are present. Skills under %USERPROFILE%\.copilot\skills without this policy are also present.

Expected behavior

Once an interactive slash command has resolved a skill and supplied its <skill-context>, the assistant should execute those instructions directly. It should not call the model-facing skill() tool again.

allow_implicit_invocation: false should prevent automatic model selection without breaking a direct /skill invocation that the CLI has already resolved.

Additional context

• OS: Microsoft Windows 10.0.26200, x64
• PowerShell: 7.6.4
• Model: GPT-5.6 Sol
• Related registry/filtering issue: #4438

Debug logs available on request.

从交互式 /skill resolver 和面向模型的 skill() registry 路径开始，以 agents/openai.yaml policy 以及相关 issue #4438 中描述的行为作为上下文。跟踪显式 invocation 在解析后如何传递，然后验证 allow_implicit_invocation: false 仍会将 skills 排除在自动选择之外，且不会导致第二次查找；使用 /implement 5514365 复现，以确认 workflow 启动。