feat: Add skill discovery, loading, and invocation (#3444)

Adds a skills system that lets users define reusable LLM instructions as `SKILL.md` files with YAML frontmatter.

1 files changed, 50 insertions, 0 deletions

diff --git a/crates/atuin-ai/src/fsm/mod.rs b/crates/atuin-ai/src/fsm/mod.rs
index 25de41f3..3d72a3ae 100644
--- a/crates/atuin-ai/src/fsm/mod.rs
+++ b/crates/atuin-ai/src/fsm/mod.rs
@@ -309,6 +309,33 @@ impl AgentFsm {
                 vec![]
             }
 
+            (
+                AgentState::Idle { .. },
+                Event::SkillLoaded {
+                    name,
+                    arguments,
+                    content,
+                },
+            ) => {
+                self.ctx.events.push(ConversationEvent::SkillInvocation {
+                    name,
+                    arguments,
+                    content,
+                });
+                self.ctx.current_response.clear();
+                self.ctx.current_turn_tool_ids.clear();
+
+                let messages = self.build_messages();
+                let session_id = self.ctx.session_id.clone();
+                self.state = AgentState::Turn {
+                    stream: StreamPhase::Connecting,
+                };
+                vec![Effect::StartStream {
+                    messages,
+                    session_id,
+                }]
+            }
+
             // ================================================================
             // Turn — stream lifecycle
             // ================================================================
@@ -584,6 +611,29 @@ impl AgentFsm {
                 vec![]
             }
 
+            // RequestSkillLoad during non-idle: still emit the effect
+            (_, Event::RequestSkillLoad { name, arguments }) => {
+                vec![Effect::LoadSkill { name, arguments }]
+            }
+
+            // SkillLoaded during non-idle: queue so it's visible
+            // in context for the next turn.
+            (
+                _,
+                Event::SkillLoaded {
+                    name,
+                    arguments,
+                    content,
+                },
+            ) => {
+                self.ctx.events.push(ConversationEvent::SkillInvocation {
+                    name,
+                    arguments,
+                    content,
+                });
+                vec![]
+            }
+
             _ => vec![],
         }
     }