docs: intent for fix-context-set-skill

docs/features/fix-context-set-skill.md

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+---
+feature_ids: [fix-context-set-skill]
+topics: [context, skill, auto_skill_mode, bugfix]
+doc_kind: feature
+created: 2026-03-25
+status: active
+---
+
+# fix-context-set-skill: Fix AttributeError crash in auto_skill_mode
+
+> Status: active | Owner: tianyiliang
+
+## Why
+
+When `enable_skill_tool=True` (the default), the LLM can call `search_skill` to dynamically select a skill at runtime. After the tool returns, `execute_engine` invokes `DareAgent._mount_skill_from_result`, which calls `context.set_skill()`. However, neither `IContext` nor `Context` defines `set_skill`, causing an uncaught `AttributeError` that crashes the execute loop.
+
+This means auto_skill_mode is completely broken — the only usable path is persistent_skill_mode (`enable_skill_tool=False`).
+
+## What
+
+- Add `set_skill(self, skill: Skill | None) -> None` to `IContext` (kernel.py) as an abstract method
+- Add concrete implementation in `Context` (context.py)
+
+## Acceptance Criteria
+
+- [ ] AC-1: `IContext` declares `set_skill` abstract method (consistent with `set_tool_gateway` pattern)
+- [ ] AC-2: `Context.set_skill()` sets `_sys_skill` field
+- [ ] AC-3: `_mount_skill_from_result` no longer raises `AttributeError` when `enable_skill_tool=True`
+- [ ] AC-4: Persistent skill mode (`enable_skill_tool=False`) is unaffected
+
+## Dependencies
+
+None.
+
+## Risk
+
+Low — additive change only.
+
+## Open Questions
+
+None.
+
+### Review and Merge Gate Links
+
+- Intent PR: (this document)