feat(backend): domaine + catalogue et store durable des permissions tools MCP (#82 lot B1)

Introduit le domaine mcp_tool_permissions (règles de permission par tool
MCP) et étend le port de store correspondant. Le catalogue read/write des
tools MCP (orchestrator/mcp/tools.rs) s'appuie désormais sur ces règles, et
un store durable (mcp_tool_permission.rs) persiste les permissions au-delà
d'une session.

Lot B1 du ticket #82 : pose le socle domaine/store, l'enforcement suit en
B2 sur la même branche.

QA vert.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

crates/infrastructure/src/orchestrator/mcp/tools.rs

@@ -34,6 +34,70 @@ pub struct ToolDef {
     pub input_schema: Value,
 }
 
+/// Coarse MCP tool access class used to derive default permissions.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum McpToolAccess {
+    /// Read-only application capability, allowed by default.
+    Read,
+    /// Write/action/execution capability, denied by default.
+    WriteAction,
+}
+
+/// Canonical read-only MCP tools allowed by default.
+pub const READ_ONLY_TOOLS: &[&str] = &[
+    "idea_list_agents",
+    "idea_context_read",
+    "idea_memory_read",
+    "idea_skill_read",
+    "idea_workstate_read",
+    "idea_ticket_read",
+    "idea_ticket_list",
+    "idea_ticket_read_carnet",
+    "idea_sprint_list",
+];
+
+/// Canonical write/action MCP tools denied by default.
+pub const WRITE_ACTION_TOOLS: &[&str] = &[
+    "idea_ask_agent",
+    "idea_run_in_background",
+    "idea_launch_agent",
+    "idea_stop_agent",
+    "idea_update_context",
+    "idea_context_propose",
+    "idea_memory_write",
+    "idea_workstate_set",
+    "idea_create_skill",
+    "idea_ticket_create",
+    "idea_ticket_update",
+    "idea_ticket_update_status",
+    "idea_ticket_update_priority",
+    "idea_ticket_update_carnet",
+    "idea_ticket_link",
+    "idea_ticket_unlink",
+];
+
+/// All MCP tool names that have an explicit access classification.
+#[must_use]
+pub fn classified_tool_names() -> Vec<&'static str> {
+    READ_ONLY_TOOLS
+        .iter()
+        .chain(WRITE_ACTION_TOOLS.iter())
+        .copied()
+        .collect()
+}
+
+/// Returns the explicit access class for `tool`.
+#[must_use]
+pub fn tool_access(tool: &str) -> Option<McpToolAccess> {
+    if READ_ONLY_TOOLS.contains(&tool) {
+        Some(McpToolAccess::Read)
+    } else if WRITE_ACTION_TOOLS.contains(&tool) {
+        Some(McpToolAccess::WriteAction)
+    } else {
+        None
+    }
+}
+
 /// Errors mapping a tool call into a validated [`OrchestratorCommand`].
 #[derive(Debug, thiserror::Error, PartialEq, Eq)]
 pub enum ToolMapError {
@@ -498,6 +562,7 @@ fn optional_u64(value: Option<&Value>, tool: &str) -> Result<Option<u64>, ToolMa
 mod tests {
     use super::*;
     use domain::OrchestratorVisibility;
+    use std::collections::HashSet;
 
     /// A well-formed handshake requester id for the tests (parsed as an `AgentId`).
     const REQ: &str = "11111111-1111-1111-1111-111111111111";
@@ -507,6 +572,44 @@ mod tests {
         map_tool_call(name, args, "")
     }
 
+    #[test]
+    fn catalogue_tools_have_explicit_read_or_write_access() {
+        let catalogue_names = catalogue()
+            .into_iter()
+            .map(|tool| tool.name)
+            .collect::<HashSet<_>>();
+
+        for tool in &catalogue_names {
+            assert!(
+                tool_access(tool).is_some(),
+                "MCP catalogue tool `{tool}` must choose Read or WriteAction explicitly"
+            );
+        }
+
+        for tool in classified_tool_names() {
+            assert!(
+                catalogue_names.contains(tool),
+                "classified MCP tool `{tool}` is not advertised by the catalogue"
+            );
+        }
+    }
+
+    #[test]
+    fn read_and_write_tool_classifications_are_disjoint_and_unique() {
+        let mut seen = HashSet::new();
+        for tool in READ_ONLY_TOOLS {
+            assert!(seen.insert(*tool), "duplicate read-only MCP tool `{tool}`");
+            assert_eq!(tool_access(tool), Some(McpToolAccess::Read));
+        }
+        for tool in WRITE_ACTION_TOOLS {
+            assert!(
+                seen.insert(*tool),
+                "MCP tool `{tool}` is classified more than once"
+            );
+            assert_eq!(tool_access(tool), Some(McpToolAccess::WriteAction));
+        }
+    }
+
     #[test]
     fn ask_agent_maps_to_headless_inter_agent_command_but_reply_stays_hidden() {
         let requester = uuid::Uuid::from_u128(42).to_string();