feat(skill): add invocation controls

examples/acp-agent/tests/snapshots/skill-load/session.jsonl

@@ -2,7 +2,7 @@
 {"type":"turn/start","seq":0,"time":1783654655602,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783654655603,"data":{"content":[{"type":"text","text":"Load the snapshot-skill skill with the skill tool, then reply DONE."}],"source":{"kind":"user"}},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783654655603,"data":{"title":"Load the snapshot-skill skill with","messageSeqs":[1],"source":{"kind":"fallback"}}}
-{"type":"user/message","seq":3,"time":1784903324926,"data":{"content":[{"type":"text","text":"<system-reminder>\nA skill is a reusable set of task-specific instructions. The following skills are available in this session:\n\n<available_skills>\n- `snapshot-skill`: Exercise project skill discovery and loading in snapshot tests.\n</available_skills>\n\nIf the user names a skill, or the task clearly matches a skill's description, call the `skill` tool with the exact skill name before taking task actions. Load all applicable skills, then follow their full instructions. This catalog contains summaries only; do not infer or follow a skill's instructions until it has been loaded.\n</system-reminder>"}],"source":{"kind":"plugin","plugin":"dsh-tool-skill"}},"surfaceOp":"append"}
+{"type":"user/message","seq":3,"time":1784903324926,"data":{"content":[{"type":"text","text":"<system-reminder>\nA skill is a reusable set of task-specific instructions. The following skills are available in this session:\n\n<available_skills>\n- `model-only-skill`: Prove user-disabled skills remain available to the model.\n- `snapshot-skill`: Exercise project skill discovery and loading in snapshot tests.\n</available_skills>\n\nIf the user names a skill, or the task clearly matches a skill's description, call the `skill` tool with the exact skill name before taking task actions. Load all applicable skills, then follow their full instructions. This catalog contains summaries only; do not infer or follow a skill's instructions until it has been loaded.\n</system-reminder>"}],"source":{"kind":"plugin","plugin":"dsh-tool-skill"}},"surfaceOp":"append"}
 {"type":"step/start","seq":4,"time":1784903324927,"data":{"turn":1,"step":1}}
 {"type":"request/header","seq":5,"time":1784903324928,"data":{"header":{"config":{"provider":"deepseek","model":"deepseek-v4-flash"},"system":"{{system}}","tools":"{{tools}}"},"reason":"initial"}}
 {"type":"assistant/chunk","seq":6,"time":1783654655609,"data":{"turn":1,"step":1,"chunk":{"type":"block-start","index":0,"blockType":"reasoning"}}}

examples/acp-agent/tests/snapshots/skill-load/workspace/.dsh/skills/model-only-skill/SKILL.md

@@ -0,0 +1,7 @@
+---
+name: model-only-skill
+description: Prove user-disabled skills remain available to the model.
+user-invocable: false
+---
+
+Follow these model-only snapshot instructions.

examples/acp-agent/tests/snapshots/skill-load/workspace/.dsh/skills/user-only-skill/SKILL.md

@@ -0,0 +1,7 @@
+---
+name: user-only-skill
+description: Prove model-disabled skills stay outside the model catalog.
+disable-model-invocation: true
+---
+
+Follow these user-only snapshot instructions.

examples/tui-agent/tests/tui-keyless-smoke.e2e.ts

@@ -219,6 +219,8 @@ describe('tui-agent keyless smoke (real Loader tree in a PTY)', () => {
             '---',
             'name: scripted-skill',
             'description: Keyless PTY proof that the skill command loads a local skill into the conversation.',
+            'disable-model-invocation: true',
+            'user-invocable: true',
             '---',
             '',
             'SCRIPTED SKILL BODY MARKER',