feat: Client-tool execution + permission system (#3370)

Adds client-side tool execution to Atuin AI, starting with
`atuin_history`. The server can request tool calls, which are executed
locally with a permission system, and results are sent back to continue
the conversation.

1 files changed, 74 insertions, 0 deletions

diff --git a/crates/atuin-ai/src/permissions/check.rs b/crates/atuin-ai/src/permissions/check.rs
new file mode 100644
index 00000000..6b908b93
--- /dev/null
+++ b/crates/atuin-ai/src/permissions/check.rs
@@ -0,0 +1,74 @@
+use eyre::Result;
+
+use crate::{permissions::file::RuleFile, tools::PermissableToolCall};
+
+pub(crate) struct PermissionRequest<'t> {
+    call: &'t (dyn PermissableToolCall + Send + Sync),
+}
+
+impl<'t> PermissionRequest<'t> {
+    pub fn new(call: &'t (dyn PermissableToolCall + Send + Sync)) -> Self {
+        Self { call }
+    }
+}
+
+pub(crate) enum PermissionResponse {
+    Allowed,
+    Denied,
+    Ask,
+}
+
+pub(crate) struct PermissionChecker {
+    files: Vec<RuleFile>,
+}
+
+impl PermissionChecker {
+    pub fn new(files: Vec<RuleFile>) -> Self {
+        Self { files }
+    }
+
+    pub async fn check<'t>(
+        &self,
+        request: &'t PermissionRequest<'t>,
+    ) -> Result<PermissionResponse> {
+        // Files are in order from deepest to shallowest, so we can stop at the first match.
+        // Within a file, the priority is ask -> deny -> allow
+        // The first rule type that matches is the one that applies, even if a later rule would contradict it.
+        for file in &self.files {
+            for rule in &file.content.permissions.ask {
+                if request.call.matches_rule(rule) {
+                    tracing::debug!(
+                        "Permission 'ASK' by rule: {} in file: {}",
+                        rule,
+                        file.path.display()
+                    );
+                    return Ok(PermissionResponse::Ask);
+                }
+            }
+
+            for rule in &file.content.permissions.deny {
+                if request.call.matches_rule(rule) {
+                    tracing::debug!(
+                        "Permission 'DENY' by rule: {} in file: {}",
+                        rule,
+                        file.path.display()
+                    );
+                    return Ok(PermissionResponse::Denied);
+                }
+            }
+
+            for rule in &file.content.permissions.allow {
+                if request.call.matches_rule(rule) {
+                    tracing::debug!(
+                        "Permission 'ALLOW' by rule: {} in file: {}",
+                        rule,
+                        file.path.display()
+                    );
+                    return Ok(PermissionResponse::Allowed);
+                }
+            }
+        }
+
+        Ok(PermissionResponse::Ask)
+    }
+}