feat(agent): conversation par paire + entrée médiée + pivot terminal/MCP

Coeur inter-agents consolidé et surface front réalignée sur la décision
"terminal natif PTY, pas d'UI chat" (Option 1).

Domaine
- nouveaux modules conversation, mailbox, input, fileguard (ports + types)
- orchestrator/profile/events étendus (conversation par paire, FIFO)

Application / Infrastructure
- orchestrator/service + context_guard : sérialisation FIFO par agent,
  garde RW mémoire/contexte, dispatch ask/reply
- adapters in-memory conversation / mailbox / input / fileguard
- registry session + lifecycle agent durcis (1 agent = 1 session vivante)
- outils MCP idea_* alignés sur le nouveau dispatch

Frontend
- MediatedInput + useAgentBusy : entrée utilisateur médiée par IdeA,
  terminal = vue sortie inchangée
- suppression de la vue chat structurée (AgentChatView) — abandonnée
- adapter input + ports mis à jour

Divers
- .ideai/ : mémoire projet + briefs de cadrage versionnés ;
  requests/ runtime ignoré ; agents projet réels (DevBackend/DevFrontend/QA)

Tests : Rust (domain/application/infrastructure/app-tauri) + front (346) verts.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

crates/application/src/agent/lifecycle.rs

@@ -1750,6 +1750,17 @@ pub(crate) fn compose_convention_file(
              (lister les agents du projet). IdeA lancera ou réattachera l'agent cible \
              avec son propre AI Profile, son contexte et sa mémoire.\n\n",
         );
+        // Protocole de délégation (Option 1, B-5) : côté agent SOLLICITÉ. Une tâche
+        // déléguée arrive dans ton terminal préfixée `[IdeA · tâche de … · ticket …]`.
+        // Tu DOIS y répondre via l'outil `idea_reply`, jamais en texte libre — sinon
+        // l'agent qui t'a sollicité reste bloqué (sa réponse ne lui parviendra pas).
+        out.push_str(
+            "Quand tu reçois une tâche déléguée par IdeA (un message préfixé \
+             `[IdeA · tâche de … · ticket …]`), traite-la puis appelle \
+             **impérativement** l'outil `idea_reply(result=…)` pour rendre ton \
+             résultat. Ne réponds **jamais** uniquement en texte : seul `idea_reply` \
+             débloque l'agent qui t'a sollicité.\n\n",
+        );
     } else {
         out.push_str(
             "Pour déléguer une tâche à un autre agent, n'utilise jamais les subagents \
@@ -1785,6 +1796,7 @@ pub(crate) fn compose_convention_file(
             out.push_str("- [");
             out.push_str(&entry.title);
             out.push_str("](");
+            out.push_str(".ideai/memory/");
             out.push_str(entry.slug.as_str());
             out.push_str(".md) — ");
             out.push_str(&entry.hook);
@@ -1998,9 +2010,13 @@ mod tests {
         let section_at = doc.find("# Mémoire projet").unwrap();
         assert!(persona_at < section_at, "memory comes after the persona");
 
-        // Exact line format: `- [Title](slug.md) — hook (type)`.
-        assert!(doc.contains("- [Alpha](alpha-note.md) — the first hook (user)"));
-        assert!(doc.contains("- [Beta](beta-note.md) — the second hook (reference)"));
+        // Exact line format: `- [Title](.ideai/memory/slug.md) — hook (type)`.
+        assert!(doc.contains("- [Alpha](.ideai/memory/alpha-note.md) — the first hook (user)"));
+        assert!(
+            doc.contains(
+                "- [Beta](.ideai/memory/beta-note.md) — the second hook (reference)"
+            )
+        );
 
         // Deterministic order: first entry precedes the second.
         let alpha_at = doc.find("[Alpha]").unwrap();
@@ -2033,7 +2049,7 @@ mod tests {
         assert!(doc.contains("# Skills"));
         assert!(doc.contains("REFAC_BODY"));
         assert!(doc.contains("# Mémoire projet"));
-        assert!(doc.contains("- [Note](note.md) — a hook (project)"));
+        assert!(doc.contains("- [Note](.ideai/memory/note.md) — a hook (project)"));
 
         // Skills section precedes the memory section (persona → skills → memory).
         let skills_at = doc.find("# Skills").unwrap();
@@ -2066,6 +2082,25 @@ mod tests {
         );
     }
 
+    #[test]
+    fn compose_convention_file_mcp_prose_carries_the_idea_reply_delegation_protocol() {
+        // B-5 — the solicited-agent side of the protocol: a delegated task arrives as
+        // `[IdeA · tâche …]` and MUST be answered via `idea_reply`, never plain text.
+        let doc = compose_convention_file("/root", "", "# Persona", &[], &[], true);
+        assert!(
+            doc.contains("idea_reply"),
+            "MCP prose must instruct answering via idea_reply"
+        );
+        assert!(
+            doc.contains("[IdeA · tâche"),
+            "MCP prose must describe the delegated-task prefix it answers to"
+        );
+        // Negative: the non-MCP (file-protocol) prose must NOT carry the idea_reply
+        // instruction (zero regression on the file path).
+        let file_doc = compose_convention_file("/root", "", "# Persona", &[], &[], false);
+        assert!(!file_doc.contains("idea_reply"));
+    }
+
     #[test]
     fn compose_convention_file_non_mcp_prose_is_the_unchanged_file_protocol() {
         // mcp_enabled = false ⇒ the current `.ideai/requests` wording, unchanged,
@@ -2087,6 +2122,60 @@ mod tests {
         );
     }
 
+    #[test]
+    fn mcp_declaration_with_runtime_points_the_bridge_at_the_real_endpoint() {
+        // B-0 — a PTY-launched MCP-capable CLI (Claude/Codex REPL) auto-discovers the
+        // `.mcp.json` in its cwd (the run dir). When the composition root injects the
+        // real `McpRuntime`, the declaration written there must spawn *this* IdeA exe
+        // in `mcp-server` mode and dial the project's exact loopback endpoint — the
+        // same source of truth `ensure_mcp_server` binds — so the CLI can call
+        // `idea_list_agents` and get a reply end-to-end.
+        let rt = McpRuntime {
+            exe: "/opt/idea/idea".to_owned(),
+            endpoint: "/run/user/1000/idea-mcp/proj.sock".to_owned(),
+            project_id: "0123456789abcdef0123456789abcdef".to_owned(),
+            requester: "11112222-3333-4444-5555-666677778888".to_owned(),
+        };
+        let decl = mcp_server_declaration(domain::profile::McpTransport::Stdio, Some(&rt));
+
+        // It is valid JSON with the IdeA server under `mcpServers/idea`.
+        let parsed: serde_json::Value =
+            serde_json::from_str(&decl).expect("declaration is valid JSON");
+        let idea = &parsed["mcpServers"]["idea"];
+        assert_eq!(idea["command"], "/opt/idea/idea");
+        let args = idea["args"].as_array().expect("args is an array");
+        let args: Vec<&str> = args.iter().filter_map(serde_json::Value::as_str).collect();
+        assert_eq!(args[0], "mcp-server");
+        // The real endpoint / project / requester are all threaded through.
+        assert!(args.contains(&"--endpoint"));
+        assert!(args.contains(&"/run/user/1000/idea-mcp/proj.sock"));
+        assert!(args.contains(&"--project"));
+        assert!(args.contains(&"0123456789abcdef0123456789abcdef"));
+        assert!(args.contains(&"--requester"));
+        assert_eq!(idea["transport"], "stdio");
+    }
+
+    #[test]
+    fn mcp_declaration_without_runtime_is_a_coherent_minimal_fallback() {
+        // Launches issued from inside `application` (orchestrator/hot-swap/tests) have
+        // no OS/runtime facts: the declaration falls back to the bare `idea mcp-server`
+        // command — still a valid, self-consistent `mcpServers/idea` entry.
+        let decl = mcp_server_declaration(domain::profile::McpTransport::Stdio, None);
+        let parsed: serde_json::Value =
+            serde_json::from_str(&decl).expect("minimal declaration is valid JSON");
+        let idea = &parsed["mcpServers"]["idea"];
+        assert_eq!(idea["command"], "idea");
+        let args: Vec<&str> = idea["args"]
+            .as_array()
+            .expect("args array")
+            .iter()
+            .filter_map(serde_json::Value::as_str)
+            .collect();
+        assert_eq!(args, vec!["mcp-server"]);
+        // No endpoint/project/requester when no runtime was injected.
+        assert!(!args.contains(&"--endpoint"));
+    }
+
     #[test]
     fn claude_settings_seed_grants_autonomy_and_keeps_guardrails() {
         let json = claude_settings_seed("/home/me/proj");

crates/application/src/lib.rs

@@ -71,7 +71,7 @@ pub use memory::{
     RecallMemoryInput, RecallMemoryOutput, ResolveMemoryLinks, ResolveMemoryLinksInput,
     ResolveMemoryLinksOutput, UpdateMemory, UpdateMemoryInput, UpdateMemoryOutput,
 };
-pub use orchestrator::{OrchestratorOutcome, OrchestratorService};
+pub use orchestrator::{McpRuntimeProvider, OrchestratorOutcome, OrchestratorService};
 pub use project::{
     CloseProject, CloseProjectInput, CloseProjectOutput, CloseTab, CloseTabInput, CreateProject,
     CreateProjectInput, CreateProjectOutput, ListProjects, ListProjectsOutput, OpenProject,

crates/application/src/orchestrator/context_guard.rs

@@ -0,0 +1,819 @@
+//! FileGuard-mediated context & memory use cases (cadrage C7).
+//!
+//! Four use cases — [`ReadContext`], [`ProposeContext`], [`ReadMemory`],
+//! [`WriteMemory`] — route every read/write of IdeA-owned `.md` context and memory
+//! through the domain [`FileGuard`] port **before** touching a store. Each acquires
+//! the right lease (shared read / exclusive write) for the requesting
+//! [`ConversationParty`], then delegates to the existing store ports.
+//!
+//! ## Single-writer global context
+//!
+//! The global project context is single-writer: only the orchestrator
+//! ([`ConversationParty::User`]) may write it directly. A project agent that
+//! *proposes* a change to the global context receives [`GuardError::Forbidden`] from
+//! the guard; [`ProposeContext`] catches that and **materialises a proposal** under
+//! `.ideai/proposals/<who>-<ts>.md` for later validation by the orchestrator/UI —
+//! never overwriting the live context. An agent's *own* `.md` (and memory) is written
+//! directly under a write-lease.
+//!
+//! ## Cooperative scope (cadrage §9.5)
+//!
+//! The guard is **cooperative**: it serialises access inside the IdeA path (these use
+//! cases + the MCP tools). It does **not** sandbox an agent that keeps a raw shell —
+//! airtight revocation of raw fs access is an OS-sandbox (Landlock) concern, out of
+//! scope here.
+
+use std::sync::Arc;
+
+use domain::conversation::ConversationParty;
+use domain::fileguard::{FileGuard, GuardError, GuardedResource};
+use domain::markdown::MarkdownDoc;
+use domain::memory::{Memory, MemoryFrontmatter, MemorySlug, MemoryType};
+use domain::ports::{
+    AgentContextStore, Clock, FileSystem, MemoryStore, RemotePath,
+};
+use domain::{AgentId, Project};
+
+use crate::error::AppError;
+
+/// Convention filename of the project's global context at the project root.
+const PROJECT_CONTEXT_FILE: &str = "CLAUDE.md";
+/// `.ideai/` subdirectory where a rejected global-context change is materialised.
+const PROPOSALS_DIR: &str = ".ideai/proposals";
+
+/// Joins a project root with a POSIX-relative segment (valid on every target).
+fn join_root(project: &Project, rel: &str) -> RemotePath {
+    let base = project.root.as_str().trim_end_matches(['/', '\\']);
+    RemotePath::new(format!("{base}/{rel}"))
+}
+
+/// Resolves an agent display name to its [`AgentId`] via the project manifest
+/// (case-insensitive), or [`AppError::NotFound`].
+async fn resolve_agent(
+    contexts: &Arc<dyn AgentContextStore>,
+    project: &Project,
+    name: &str,
+) -> Result<AgentId, AppError> {
+    let manifest = contexts.load_manifest(project).await?;
+    manifest
+        .entries
+        .into_iter()
+        .find(|e| e.name.eq_ignore_ascii_case(name))
+        .map(|e| e.agent_id)
+        .ok_or_else(|| AppError::NotFound(format!("agent `{name}`")))
+}
+
+/// Reads an IdeA-owned context under a **shared read-lease** ([`GuardedResource`]).
+///
+/// `target` absent ⇒ the global project context; otherwise the named agent's `.md`.
+pub struct ReadContext {
+    guard: Arc<dyn FileGuard>,
+    contexts: Arc<dyn AgentContextStore>,
+    fs: Arc<dyn FileSystem>,
+}
+
+/// Input for [`ReadContext`].
+pub struct ReadContextInput {
+    /// The project to read within.
+    pub project: Project,
+    /// Target agent display name; `None` ⇒ the global project context.
+    pub target: Option<String>,
+    /// The reading party (drives the read-lease holder identity).
+    pub requester: ConversationParty,
+}
+
+impl ReadContext {
+    /// Builds the use case from its ports.
+    #[must_use]
+    pub fn new(
+        guard: Arc<dyn FileGuard>,
+        contexts: Arc<dyn AgentContextStore>,
+        fs: Arc<dyn FileSystem>,
+    ) -> Self {
+        Self { guard, contexts, fs }
+    }
+
+    /// Reads the requested context, returning its Markdown body.
+    ///
+    /// # Errors
+    /// [`AppError`] when the agent/context does not exist or the store/fs fails.
+    pub async fn execute(&self, input: ReadContextInput) -> Result<MarkdownDoc, AppError> {
+        let ReadContextInput { project, target, requester } = input;
+        match target {
+            None => {
+                // Global project context: shared read-lease, then read the root file.
+                let _lease = self
+                    .guard
+                    .acquire_read(requester, GuardedResource::ProjectContext)
+                    .await
+                    .map_err(map_guard_err)?;
+                let path = join_root(&project, PROJECT_CONTEXT_FILE);
+                let bytes = self.fs.read(&path).await?;
+                let text = String::from_utf8(bytes)
+                    .map_err(|e| AppError::Invalid(e.to_string()))?;
+                Ok(MarkdownDoc::new(text))
+            }
+            Some(name) => {
+                let agent = resolve_agent(&self.contexts, &project, &name).await?;
+                let _lease = self
+                    .guard
+                    .acquire_read(requester, GuardedResource::AgentContext(agent))
+                    .await
+                    .map_err(map_guard_err)?;
+                Ok(self.contexts.read_context(&project, &agent).await?)
+            }
+        }
+    }
+}
+
+/// Proposes new content for an IdeA-owned context under the [`FileGuard`].
+///
+/// For an **agent** context: a direct write under an exclusive write-lease. For the
+/// **global** project context by a non-orchestrator: the guard returns
+/// [`GuardError::Forbidden`], which this use case turns into a *materialised proposal*
+/// (a file under `.ideai/proposals/`) — never an overwrite of the live context.
+pub struct ProposeContext {
+    guard: Arc<dyn FileGuard>,
+    contexts: Arc<dyn AgentContextStore>,
+    fs: Arc<dyn FileSystem>,
+    clock: Arc<dyn Clock>,
+}
+
+/// Outcome of a [`ProposeContext`] call: whether it wrote directly or filed a proposal.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ProposeOutcome {
+    /// The content was written directly (agent context, or global by the orchestrator).
+    Written,
+    /// A proposal was materialised at the given `.ideai/proposals/…` path (a
+    /// non-orchestrator targeting the single-writer global context).
+    Proposed {
+        /// The proposal file's path.
+        path: String,
+    },
+}
+
+/// Input for [`ProposeContext`].
+pub struct ProposeContextInput {
+    /// The project to write within.
+    pub project: Project,
+    /// Target agent display name; `None` ⇒ the global project context.
+    pub target: Option<String>,
+    /// The proposed Markdown body.
+    pub content: String,
+    /// The proposing party.
+    pub requester: ConversationParty,
+}
+
+impl ProposeContext {
+    /// Builds the use case from its ports.
+    #[must_use]
+    pub fn new(
+        guard: Arc<dyn FileGuard>,
+        contexts: Arc<dyn AgentContextStore>,
+        fs: Arc<dyn FileSystem>,
+        clock: Arc<dyn Clock>,
+    ) -> Self {
+        Self { guard, contexts, fs, clock }
+    }
+
+    /// Applies the proposal: direct write under a write-lease, or a materialised
+    /// proposal when the guard forbids a direct global-context write.
+    ///
+    /// # Errors
+    /// [`AppError`] when the agent does not exist or the store/fs fails.
+    pub async fn execute(&self, input: ProposeContextInput) -> Result<ProposeOutcome, AppError> {
+        let ProposeContextInput { project, target, content, requester } = input;
+        match target {
+            Some(name) => {
+                // Per-agent context: direct write under an exclusive write-lease.
+                let agent = resolve_agent(&self.contexts, &project, &name).await?;
+                let _lease = self
+                    .guard
+                    .acquire_write(requester, GuardedResource::AgentContext(agent))
+                    .await
+                    .map_err(map_guard_err)?;
+                self.contexts
+                    .write_context(&project, &agent, &MarkdownDoc::new(content))
+                    .await?;
+                Ok(ProposeOutcome::Written)
+            }
+            None => {
+                // Global project context: single-writer. Try to acquire the write
+                // lease; Forbidden ⇒ materialise a proposal instead of overwriting.
+                match self
+                    .guard
+                    .acquire_write(requester, GuardedResource::ProjectContext)
+                    .await
+                {
+                    Ok(_lease) => {
+                        let path = join_root(&project, PROJECT_CONTEXT_FILE);
+                        self.fs.write(&path, content.as_bytes()).await?;
+                        Ok(ProposeOutcome::Written)
+                    }
+                    Err(GuardError::Forbidden) => {
+                        let path = self.file_proposal(&project, requester, &content).await?;
+                        Ok(ProposeOutcome::Proposed { path })
+                    }
+                    Err(other) => Err(map_guard_err(other)),
+                }
+            }
+        }
+    }
+
+    /// Materialises a rejected global-context change as a proposal file under
+    /// `.ideai/proposals/<who>-<ts>.md`, returning its path.
+    async fn file_proposal(
+        &self,
+        project: &Project,
+        who: ConversationParty,
+        content: &str,
+    ) -> Result<String, AppError> {
+        let who_label = match who {
+            ConversationParty::User => "orchestrator".to_owned(),
+            ConversationParty::Agent { agent_id } => agent_id.to_string(),
+        };
+        let ts = self.clock.now_millis();
+        let rel = format!("{PROPOSALS_DIR}/{who_label}-{ts}.md");
+        let dir = join_root(project, PROPOSALS_DIR);
+        self.fs.create_dir_all(&dir).await?;
+        let path = join_root(project, &rel);
+        self.fs.write(&path, content.as_bytes()).await?;
+        Ok(path.as_str().to_owned())
+    }
+}
+
+/// Reads project memory under a shared read-lease.
+///
+/// `slug` absent ⇒ the aggregated index (as Markdown lines); otherwise one note's body.
+pub struct ReadMemory {
+    guard: Arc<dyn FileGuard>,
+    memory: Arc<dyn MemoryStore>,
+}
+
+/// Input for [`ReadMemory`].
+pub struct ReadMemoryInput {
+    /// The project to read within.
+    pub project: Project,
+    /// Target note slug; `None` ⇒ the aggregated index.
+    pub slug: Option<String>,
+    /// The reading party.
+    pub requester: ConversationParty,
+}
+
+impl ReadMemory {
+    /// Builds the use case from its ports.
+    #[must_use]
+    pub fn new(guard: Arc<dyn FileGuard>, memory: Arc<dyn MemoryStore>) -> Self {
+        Self { guard, memory }
+    }
+
+    /// Reads the requested memory, returning its Markdown content.
+    ///
+    /// # Errors
+    /// [`AppError`] when the note does not exist or the store fails. An invalid slug
+    /// is [`AppError::Invalid`].
+    pub async fn execute(&self, input: ReadMemoryInput) -> Result<String, AppError> {
+        let ReadMemoryInput { project, slug, requester } = input;
+        match slug {
+            Some(raw) => {
+                let slug = MemorySlug::new(raw).map_err(|e| AppError::Invalid(e.to_string()))?;
+                let _lease = self
+                    .guard
+                    .acquire_read(requester, GuardedResource::Memory(slug.clone()))
+                    .await
+                    .map_err(map_guard_err)?;
+                let note = self.memory.get(&project.root, &slug).await?;
+                Ok(note.body.into_string())
+            }
+            None => {
+                // The aggregated index is project-shared; read it as a rendered list.
+                let entries = self.memory.read_index(&project.root).await?;
+                let lines: Vec<String> = entries
+                    .into_iter()
+                    .map(|e| format!("- [{}]({}.md) — {}", e.title, e.slug, e.hook))
+                    .collect();
+                Ok(lines.join("\n"))
+            }
+        }
+    }
+}
+
+/// Writes (creates or replaces) a project memory note under an exclusive write-lease.
+pub struct WriteMemory {
+    guard: Arc<dyn FileGuard>,
+    memory: Arc<dyn MemoryStore>,
+}
+
+/// Input for [`WriteMemory`].
+pub struct WriteMemoryInput {
+    /// The project to write within.
+    pub project: Project,
+    /// Target note slug.
+    pub slug: String,
+    /// The Markdown body to store.
+    pub content: String,
+    /// The writing party.
+    pub requester: ConversationParty,
+}
+
+impl WriteMemory {
+    /// Builds the use case from its ports.
+    #[must_use]
+    pub fn new(guard: Arc<dyn FileGuard>, memory: Arc<dyn MemoryStore>) -> Self {
+        Self { guard, memory }
+    }
+
+    /// Writes the note under a write-lease.
+    ///
+    /// # Errors
+    /// [`AppError::Invalid`] for a bad slug or empty body; [`AppError`] on a store
+    /// failure.
+    pub async fn execute(&self, input: WriteMemoryInput) -> Result<(), AppError> {
+        let WriteMemoryInput { project, slug, content, requester } = input;
+        let slug = MemorySlug::new(slug).map_err(|e| AppError::Invalid(e.to_string()))?;
+        let _lease = self
+            .guard
+            .acquire_write(requester, GuardedResource::Memory(slug.clone()))
+            .await
+            .map_err(map_guard_err)?;
+        let frontmatter = MemoryFrontmatter {
+            name: slug.clone(),
+            description: format!("memory note {slug}"),
+            r#type: MemoryType::Project,
+        };
+        let note = Memory::new(frontmatter, MarkdownDoc::new(content))
+            .map_err(|e| AppError::Invalid(e.to_string()))?;
+        self.memory.save(&project.root, &note).await?;
+        Ok(())
+    }
+}
+
+/// Maps a [`GuardError`] onto the application error shape. `Forbidden` is an invariant
+/// violation ([`AppError::Invalid`]); `Busy` is a transient contention the cooperative
+/// blocking adapter never returns, but is mapped for completeness.
+fn map_guard_err(e: GuardError) -> AppError {
+    match e {
+        GuardError::Forbidden => AppError::Invalid(
+            "writing the global project context is reserved to the orchestrator; propose instead"
+                .to_owned(),
+        ),
+        GuardError::Busy => AppError::Invalid("guarded resource is busy".to_owned()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use async_trait::async_trait;
+    use domain::agent::{AgentManifest, ManifestEntry};
+    use domain::conversation::ConversationParty;
+    use domain::fileguard::{may_write_directly, ReadLease, WriteLease};
+    use domain::ports::{FsError, MemoryError, StoreError};
+    use domain::project::ProjectPath;
+    use domain::{ProfileId, ProjectId, RemoteRef};
+    use std::collections::HashMap;
+    use std::sync::{Arc as StdArc, Mutex};
+    use std::time::Duration;
+    use tokio::sync::RwLock;
+
+    fn project() -> Project {
+        Project::new(
+            ProjectId::from_uuid(uuid::Uuid::from_u128(1)),
+            "demo",
+            ProjectPath::new("/tmp/demo").unwrap(),
+            RemoteRef::local(),
+            0,
+        )
+        .unwrap()
+    }
+
+    /// In-test [`FileGuard`] mirroring `infrastructure::RwFileGuard` (one tokio
+    /// `RwLock` per resource + the single-writer rule), so the application crate
+    /// stays free of any dependency on infrastructure (no dependency cycle).
+    #[derive(Default)]
+    struct TestGuard {
+        locks: Mutex<HashMap<GuardedResource, StdArc<RwLock<()>>>>,
+    }
+
+    impl TestGuard {
+        fn lock_for(&self, res: &GuardedResource) -> StdArc<RwLock<()>> {
+            self.locks
+                .lock()
+                .unwrap()
+                .entry(res.clone())
+                .or_insert_with(|| StdArc::new(RwLock::new(())))
+                .clone()
+        }
+    }
+
+    #[async_trait]
+    impl FileGuard for TestGuard {
+        async fn acquire_read(
+            &self,
+            _who: ConversationParty,
+            res: GuardedResource,
+        ) -> Result<ReadLease, GuardError> {
+            let lock = self.lock_for(&res);
+            Ok(ReadLease::new(Box::new(lock.read_owned().await)))
+        }
+        async fn acquire_write(
+            &self,
+            who: ConversationParty,
+            res: GuardedResource,
+        ) -> Result<WriteLease, GuardError> {
+            if !may_write_directly(who, &res) {
+                return Err(GuardError::Forbidden);
+            }
+            let lock = self.lock_for(&res);
+            Ok(WriteLease::new(Box::new(lock.write_owned().await)))
+        }
+    }
+
+    fn agent_party(n: u128) -> ConversationParty {
+        ConversationParty::agent(AgentId::from_uuid(uuid::Uuid::from_u128(n)))
+    }
+
+    // ---- Fakes -----------------------------------------------------------
+
+    #[derive(Default)]
+    struct FakeFs {
+        files: Mutex<HashMap<String, Vec<u8>>>,
+        dirs: Mutex<Vec<String>>,
+    }
+
+    #[async_trait]
+    impl FileSystem for FakeFs {
+        async fn read(&self, path: &RemotePath) -> Result<Vec<u8>, FsError> {
+            self.files
+                .lock()
+                .unwrap()
+                .get(path.as_str())
+                .cloned()
+                .ok_or_else(|| FsError::NotFound(path.as_str().to_owned()))
+        }
+        async fn write(&self, path: &RemotePath, data: &[u8]) -> Result<(), FsError> {
+            self.files
+                .lock()
+                .unwrap()
+                .insert(path.as_str().to_owned(), data.to_vec());
+            Ok(())
+        }
+        async fn exists(&self, path: &RemotePath) -> Result<bool, FsError> {
+            Ok(self.files.lock().unwrap().contains_key(path.as_str()))
+        }
+        async fn create_dir_all(&self, path: &RemotePath) -> Result<(), FsError> {
+            self.dirs.lock().unwrap().push(path.as_str().to_owned());
+            Ok(())
+        }
+        async fn list(&self, _path: &RemotePath) -> Result<Vec<domain::ports::DirEntry>, FsError> {
+            Ok(Vec::new())
+        }
+        async fn symlink(&self, _src: &RemotePath, _dst: &RemotePath) -> Result<(), FsError> {
+            Ok(())
+        }
+    }
+
+    struct FakeContexts {
+        manifest: AgentManifest,
+        contexts: Mutex<HashMap<AgentId, String>>,
+    }
+
+    #[async_trait]
+    impl AgentContextStore for FakeContexts {
+        async fn read_context(
+            &self,
+            _project: &Project,
+            agent: &AgentId,
+        ) -> Result<MarkdownDoc, StoreError> {
+            self.contexts
+                .lock()
+                .unwrap()
+                .get(agent)
+                .cloned()
+                .map(MarkdownDoc::new)
+                .ok_or(StoreError::NotFound)
+        }
+        async fn write_context(
+            &self,
+            _project: &Project,
+            agent: &AgentId,
+            md: &MarkdownDoc,
+        ) -> Result<(), StoreError> {
+            self.contexts
+                .lock()
+                .unwrap()
+                .insert(*agent, md.as_str().to_owned());
+            Ok(())
+        }
+        async fn load_manifest(&self, _project: &Project) -> Result<AgentManifest, StoreError> {
+            Ok(self.manifest.clone())
+        }
+        async fn save_manifest(
+            &self,
+            _project: &Project,
+            _manifest: &AgentManifest,
+        ) -> Result<(), StoreError> {
+            Ok(())
+        }
+    }
+
+    #[derive(Default)]
+    struct FakeMemory {
+        notes: Mutex<HashMap<String, String>>,
+    }
+
+    #[async_trait]
+    impl MemoryStore for FakeMemory {
+        async fn list(&self, _root: &ProjectPath) -> Result<Vec<Memory>, MemoryError> {
+            Ok(Vec::new())
+        }
+        async fn get(
+            &self,
+            _root: &ProjectPath,
+            slug: &MemorySlug,
+        ) -> Result<Memory, MemoryError> {
+            let body = self
+                .notes
+                .lock()
+                .unwrap()
+                .get(slug.as_str())
+                .cloned()
+                .ok_or(MemoryError::NotFound)?;
+            Memory::new(
+                MemoryFrontmatter {
+                    name: slug.clone(),
+                    description: "d".to_owned(),
+                    r#type: MemoryType::Project,
+                },
+                MarkdownDoc::new(body),
+            )
+            .map_err(|e| MemoryError::Frontmatter(e.to_string()))
+        }
+        async fn save(&self, _root: &ProjectPath, memory: &Memory) -> Result<(), MemoryError> {
+            self.notes
+                .lock()
+                .unwrap()
+                .insert(memory.slug().to_string(), memory.body.as_str().to_owned());
+            Ok(())
+        }
+        async fn delete(
+            &self,
+            _root: &ProjectPath,
+            _slug: &MemorySlug,
+        ) -> Result<(), MemoryError> {
+            Ok(())
+        }
+        async fn read_index(
+            &self,
+            _root: &ProjectPath,
+        ) -> Result<Vec<domain::memory::MemoryIndexEntry>, MemoryError> {
+            Ok(Vec::new())
+        }
+        async fn resolve_links(
+            &self,
+            _root: &ProjectPath,
+            _slug: &MemorySlug,
+        ) -> Result<Vec<domain::memory::MemoryLink>, MemoryError> {
+            Ok(Vec::new())
+        }
+    }
+
+    struct FixedClock;
+    impl Clock for FixedClock {
+        fn now_millis(&self) -> i64 {
+            42
+        }
+    }
+
+    fn guard() -> Arc<dyn FileGuard> {
+        Arc::new(TestGuard::default())
+    }
+
+    fn contexts_with(name: &str, agent: AgentId, body: &str) -> Arc<dyn AgentContextStore> {
+        let mut contexts = HashMap::new();
+        contexts.insert(agent, body.to_owned());
+        Arc::new(FakeContexts {
+            manifest: AgentManifest {
+                version: 1,
+                entries: vec![ManifestEntry {
+                    agent_id: agent,
+                    name: name.to_owned(),
+                    md_path: "agents/x.md".to_owned(),
+                    profile_id: ProfileId::from_uuid(uuid::Uuid::from_u128(99)),
+                    template_id: None,
+                    synchronized: false,
+                    synced_template_version: None,
+                    skills: Vec::new(),
+                }],
+            },
+            contexts: Mutex::new(contexts),
+        })
+    }
+
+    // ---- Tests -----------------------------------------------------------
+
+    #[tokio::test]
+    async fn read_agent_context_returns_body() {
+        let agent = AgentId::from_uuid(uuid::Uuid::from_u128(7));
+        let uc = ReadContext::new(
+            guard(),
+            contexts_with("Dev", agent, "# hello"),
+            Arc::new(FakeFs::default()),
+        );
+        let md = uc
+            .execute(ReadContextInput {
+                project: project(),
+                target: Some("dev".to_owned()), // case-insensitive
+                requester: agent_party(1),
+            })
+            .await
+            .unwrap();
+        assert_eq!(md.as_str(), "# hello");
+    }
+
+    #[tokio::test]
+    async fn read_global_context_reads_root_file() {
+        let fs = Arc::new(FakeFs::default());
+        fs.files
+            .lock()
+            .unwrap()
+            .insert("/tmp/demo/CLAUDE.md".to_owned(), b"# project".to_vec());
+        let uc = ReadContext::new(
+            guard(),
+            contexts_with("Dev", AgentId::from_uuid(uuid::Uuid::from_u128(7)), "x"),
+            fs,
+        );
+        let md = uc
+            .execute(ReadContextInput {
+                project: project(),
+                target: None,
+                requester: ConversationParty::User,
+            })
+            .await
+            .unwrap();
+        assert_eq!(md.as_str(), "# project");
+    }
+
+    #[tokio::test]
+    async fn concurrent_reads_do_not_block_each_other() {
+        // Two readers on the same global context, held at once. If the read-lease
+        // were exclusive this would deadlock; a bounded timeout proves it does not.
+        let guard = guard();
+        let r1 = guard
+            .acquire_read(ConversationParty::User, GuardedResource::ProjectContext)
+            .await
+            .unwrap();
+        let r2 = tokio::time::timeout(
+            Duration::from_millis(200),
+            guard.acquire_read(agent_party(1), GuardedResource::ProjectContext),
+        )
+        .await
+        .expect("a second reader must not block")
+        .unwrap();
+        drop((r1, r2));
+    }
+
+    #[tokio::test]
+    async fn agent_proposing_global_context_files_a_proposal_not_a_write() {
+        let fs = Arc::new(FakeFs::default());
+        fs.files
+            .lock()
+            .unwrap()
+            .insert("/tmp/demo/CLAUDE.md".to_owned(), b"# original".to_vec());
+        let uc = ProposeContext::new(
+            guard(),
+            contexts_with("Dev", AgentId::from_uuid(uuid::Uuid::from_u128(7)), "x"),
+            Arc::clone(&fs) as Arc<dyn FileSystem>,
+            Arc::new(FixedClock),
+        );
+        let outcome = uc
+            .execute(ProposeContextInput {
+                project: project(),
+                target: None,
+                content: "# hijack".to_owned(),
+                requester: agent_party(3),
+            })
+            .await
+            .unwrap();
+        // It is a *proposal*, not a write: the live context is untouched.
+        assert!(matches!(outcome, ProposeOutcome::Proposed { .. }));
+        assert_eq!(
+            fs.files.lock().unwrap().get("/tmp/demo/CLAUDE.md").unwrap(),
+            b"# original",
+            "the live global context must NOT be overwritten by a proposal"
+        );
+        // The proposal landed under .ideai/proposals/.
+        let files = fs.files.lock().unwrap();
+        assert!(files
+            .keys()
+            .any(|k| k.contains("/.ideai/proposals/") && k.ends_with("-42.md")));
+    }
+
+    #[tokio::test]
+    async fn orchestrator_writes_global_context_directly() {
+        let fs = Arc::new(FakeFs::default());
+        let uc = ProposeContext::new(
+            guard(),
+            contexts_with("Dev", AgentId::from_uuid(uuid::Uuid::from_u128(7)), "x"),
+            Arc::clone(&fs) as Arc<dyn FileSystem>,
+            Arc::new(FixedClock),
+        );
+        let outcome = uc
+            .execute(ProposeContextInput {
+                project: project(),
+                target: None,
+                content: "# new".to_owned(),
+                requester: ConversationParty::User,
+            })
+            .await
+            .unwrap();
+        assert_eq!(outcome, ProposeOutcome::Written);
+        assert_eq!(
+            fs.files.lock().unwrap().get("/tmp/demo/CLAUDE.md").unwrap(),
+            b"# new"
+        );
+    }
+
+    #[tokio::test]
+    async fn propose_agent_context_writes_directly() {
+        let agent = AgentId::from_uuid(uuid::Uuid::from_u128(7));
+        let contexts = contexts_with("Dev", agent, "# old");
+        let uc = ProposeContext::new(
+            guard(),
+            Arc::clone(&contexts),
+            Arc::new(FakeFs::default()),
+            Arc::new(FixedClock),
+        );
+        let outcome = uc
+            .execute(ProposeContextInput {
+                project: project(),
+                target: Some("Dev".to_owned()),
+                content: "# new body".to_owned(),
+                requester: agent_party(3),
+            })
+            .await
+            .unwrap();
+        assert_eq!(outcome, ProposeOutcome::Written);
+        assert_eq!(
+            contexts
+                .read_context(&project(), &agent)
+                .await
+                .unwrap()
+                .as_str(),
+            "# new body"
+        );
+    }
+
+    #[tokio::test]
+    async fn write_then_read_memory_round_trips_under_guard() {
+        let memory = Arc::new(FakeMemory::default());
+        let writer = WriteMemory::new(guard(), Arc::clone(&memory) as Arc<dyn MemoryStore>);
+        writer
+            .execute(WriteMemoryInput {
+                project: project(),
+                slug: "note-a".to_owned(),
+                content: "body".to_owned(),
+                requester: agent_party(2),
+            })
+            .await
+            .unwrap();
+
+        let reader = ReadMemory::new(guard(), Arc::clone(&memory) as Arc<dyn MemoryStore>);
+        let body = reader
+            .execute(ReadMemoryInput {
+                project: project(),
+                slug: Some("note-a".to_owned()),
+                requester: agent_party(2),
+            })
+            .await
+            .unwrap();
+        assert_eq!(body, "body");
+    }
+
+    #[tokio::test]
+    async fn writes_to_same_memory_note_serialise() {
+        // Two write leases on the same note must not overlap (exclusive writer).
+        let guard = guard();
+        let slug = GuardedResource::Memory(MemorySlug::new("n").unwrap());
+        let w1 = guard
+            .acquire_write(agent_party(1), slug.clone())
+            .await
+            .unwrap();
+        // While w1 is held, a second writer blocks; it only succeeds after release.
+        let blocked = tokio::time::timeout(
+            Duration::from_millis(100),
+            guard.acquire_write(agent_party(2), slug.clone()),
+        )
+        .await;
+        assert!(blocked.is_err(), "a second writer must block while w1 holds");
+        drop(w1);
+        let w2 = tokio::time::timeout(
+            Duration::from_millis(200),
+            guard.acquire_write(agent_party(2), slug),
+        )
+        .await
+        .expect("w2 acquires after w1 releases")
+        .unwrap();
+        drop(w2);
+    }
+}

crates/application/src/orchestrator/mod.rs

@@ -4,6 +4,11 @@
 //! use-case calls the UI makes, so an orchestrator agent can drive IdeA without
 //! ever spawning a process itself. See [`service::OrchestratorService`].
 
+mod context_guard;
 mod service;
 
-pub use service::{OrchestratorOutcome, OrchestratorService};
+pub use context_guard::{
+    ProposeContext, ProposeContextInput, ProposeOutcome, ReadContext, ReadContextInput, ReadMemory,
+    ReadMemoryInput, WriteMemory, WriteMemoryInput,
+};
+pub use service::{McpRuntimeProvider, OrchestratorOutcome, OrchestratorService};

crates/application/src/orchestrator/service.rs

@@ -19,16 +19,25 @@ use std::time::Duration;
 
 use tokio::sync::Mutex as AsyncMutex;
 
-use domain::ports::{EventBus, ProfileStore};
+use domain::conversation::{
+    ConversationParty, ConversationRegistry, SessionRef, WaitForGraph,
+};
+use domain::input::InputMediator;
+use domain::mailbox::{Ticket, TicketId};
+use domain::ports::{EventBus, ProfileStore, PtyHandle};
 use domain::{AgentId, DomainEvent, OrchestratorCommand, OrchestratorVisibility, ProfileId, Project};
 
 use crate::agent::{
-    send_blocking, CreateAgentFromScratch, CreateAgentInput, LaunchAgent, LaunchAgentInput,
-    ListAgents, ListAgentsInput, ReattachDecision, UpdateAgentContext, UpdateAgentContextInput,
+    CreateAgentFromScratch, CreateAgentInput, LaunchAgent, LaunchAgentInput, ListAgents,
+    ListAgentsInput, McpRuntime, ReattachDecision, UpdateAgentContext, UpdateAgentContextInput,
 };
 use crate::error::AppError;
+use crate::orchestrator::{
+    ProposeContext, ProposeContextInput, ProposeOutcome, ReadContext, ReadContextInput, ReadMemory,
+    ReadMemoryInput, WriteMemory, WriteMemoryInput,
+};
 use crate::skill::{CreateSkill, CreateSkillInput};
-use crate::terminal::{CloseTerminal, CloseTerminalInput, StructuredSessions, TerminalSessions};
+use crate::terminal::{CloseTerminal, CloseTerminalInput, TerminalSessions};
 
 /// Default terminal geometry for an orchestrator-launched agent cell. The UI
 /// resizes the PTY to the real cell size on attach; these are sane starting rows
@@ -61,6 +70,19 @@ const ASK_AGENT_TIMEOUT: Duration = Duration::from_secs(300);
 /// pleins d'attente.
 const ASK_QUEUE_WAIT_CAP: Duration = Duration::from_secs(600);
 
+/// Fournit les faits OS/runtime (exe + endpoint projet) pour écrire la déclaration MCP
+/// réelle quand l'orchestrateur (re)lance une cible sur le chemin `ask`. Implémenté dans
+/// app-tauri (seul détenteur de current_exe/$APPIMAGE/mcp_endpoint).
+///
+/// La couche `application` ne connaît que ce **port** : elle ne calcule jamais le chemin
+/// de l'exécutable ni l'endpoint loopback (ces faits vivent dans `app-tauri`, cadrage v5
+/// §0.3 / §7). Seules les **chaînes** d'un [`McpRuntime`] traversent la frontière.
+pub trait McpRuntimeProvider: Send + Sync {
+    /// `agent_id` = la cible relancée = le `--requester` (c'est elle qui appellera idea_reply).
+    /// `None` ⇒ dégrade vers la déclaration minimale (jamais d'échec de lancement).
+    fn runtime_for(&self, project: &Project, agent_id: AgentId) -> Option<McpRuntime>;
+}
+
 /// Dispatches validated orchestrator commands to the agent/terminal use cases.
 pub struct OrchestratorService {
     create_agent: Arc<CreateAgentFromScratch>,
@@ -71,11 +93,27 @@ pub struct OrchestratorService {
     create_skill: Arc<CreateSkill>,
     profiles: Arc<dyn ProfileStore>,
     sessions: Arc<TerminalSessions>,
-    /// Registre des sessions **structurées** (§17.5) — la cible d'un `agent.message`
-    /// y est cherchée pour le rendez-vous synchrone. Injecté au câblage via
-    /// [`Self::with_structured`] ; `None` ⇒ `AskAgent` ne peut pas être servi (les
-    /// call sites/tests legacy qui n'utilisent pas la messagerie restent verts).
-    structured: Option<Arc<StructuredSessions>>,
+    /// Médiateur d'entrée (cadrage C3 §5.2) — point de convergence unique de l'entrée
+    /// d'un agent. La cible d'un `agent.message`/`idea_ask_agent` y reçoit un ticket
+    /// (`enqueue`) dont on **attend** la résolution (`idea_reply` ⇒
+    /// [`OrchestratorCommand::Reply`]) ; son impl écrit aussi le tour dans le PTY de la
+    /// cible (livraison sérialisée, plus d'écriture ad hoc ici). Injecté via
+    /// [`Self::with_input_mediator`] ; `None` ⇒ `AskAgent`/`Reply` non servis (call
+    /// sites/tests legacy restent verts).
+    input: Option<Arc<dyn InputMediator>>,
+    /// Mailbox sous-jacent du médiateur, pour `resolve`/`resolve_ticket`/`cancel_head`
+    /// (corrélation par ticket). C'est le **même** moteur de corrélation que celui que
+    /// `input` enveloppe ; injecté ensemble via [`Self::with_input_mediator`].
+    mailbox: Option<Arc<dyn domain::mailbox::AgentMailbox>>,
+    /// Registre des conversations par paire (cadrage C3 §5.2) — résout paresseusement
+    /// le fil `A↔B` (ou `User↔B`) d'un `ask`, sépare strictement les contextes.
+    /// Injecté via [`Self::with_conversations`] ; `None` ⇒ on retombe sur un routage
+    /// par agent sans matérialisation de fil (legacy).
+    conversations: Option<Arc<dyn ConversationRegistry>>,
+    /// Graphe d'attente inter-agents (cadrage C3 §6) — arête posée à l'`enqueue` d'un
+    /// `ask` A→B, retirée au reply/timeout (RAII via le garde de tour). Sert à
+    /// **refuser** une délégation ré-entrante (A→B→…→A) avant deadlock.
+    wait_for: StdMutex<WaitForGraph>,
     /// Bus d'événements pour publier [`DomainEvent::AgentReplied`] à l'issue d'un
     /// `ask` réussi (§17.4). Injecté via [`Self::with_events`] ; `None` ⇒ pas de
     /// publication (l'`ask` fonctionne quand même).
@@ -99,6 +137,30 @@ pub struct OrchestratorService {
     /// Croissance bornée en pratique au nombre d'agents du projet ; une entrée
     /// morte ne coûte qu'un `Arc<Mutex<()>>` vide (pas de session, pas de process).
     ask_locks: StdMutex<HashMap<AgentId, Arc<AsyncMutex<()>>>>,
+    /// Fournisseur des faits OS/runtime (exe + endpoint) pour écrire la déclaration
+    /// MCP **réelle** quand `ensure_live_pty` (re)lance une cible sur le chemin `ask`
+    /// (B-3). Injecté au câblage via [`Self::with_mcp_runtime_provider`] depuis
+    /// app-tauri ; `None` ⇒ on conserve la déclaration minimale (`mcp_runtime: None`),
+    /// donc zéro régression pour les call sites/tests qui ne le branchent pas.
+    mcp_runtime_provider: Option<Arc<dyn McpRuntimeProvider>>,
+    /// FileGuard-mediated context/memory use cases (cadrage C7). Injected via
+    /// [`Self::with_context_guard`] ; `None` ⇒ les commandes `context.*`/`memory.*`
+    /// renvoient une erreur typée (call sites/tests legacy restent verts).
+    context_guard: Option<Arc<ContextGuardUseCases>>,
+}
+
+/// Bundle des quatre use cases C7 sous [`domain::fileguard::FileGuard`], injectés
+/// ensemble dans l'[`OrchestratorService`] (cadrage C7). Regroupés pour garder la
+/// signature de [`OrchestratorService::with_context_guard`] simple (un seul `Arc`).
+pub struct ContextGuardUseCases {
+    /// Lecture d'un contexte `.md` IdeA sous read-lease.
+    pub read_context: Arc<ReadContext>,
+    /// Proposition/écriture d'un contexte `.md` IdeA sous le garde.
+    pub propose_context: Arc<ProposeContext>,
+    /// Lecture mémoire sous read-lease.
+    pub read_memory: Arc<ReadMemory>,
+    /// Écriture mémoire sous write-lease.
+    pub write_memory: Arc<WriteMemory>,
 }
 
 /// Outcome of dispatching a command — a short, human-readable success summary the
@@ -137,12 +199,26 @@ impl OrchestratorService {
             create_skill,
             profiles,
             sessions,
-            structured: None,
+            input: None,
+            mailbox: None,
+            conversations: None,
+            wait_for: StdMutex::new(WaitForGraph::new()),
             events: None,
             ask_locks: StdMutex::new(HashMap::new()),
+            mcp_runtime_provider: None,
+            context_guard: None,
         }
     }
 
+    /// Branche les use cases C7 (`context.*`/`memory.*`) sous
+    /// [`domain::fileguard::FileGuard`]. Builder additif (signature de [`Self::new`]
+    /// inchangée).
+    #[must_use]
+    pub fn with_context_guard(mut self, guard: Arc<ContextGuardUseCases>) -> Self {
+        self.context_guard = Some(guard);
+        self
+    }
+
     /// Returns the per-agent **turn lock**, creating it on first use.
     ///
     /// Get-or-create under the synchronous map mutex (held only for this lookup,
@@ -157,13 +233,30 @@ impl OrchestratorService {
         Arc::clone(locks.entry(*agent_id).or_default())
     }
 
-    /// Branche le registre des sessions **structurées** (§17.5) pour servir
-    /// `agent.message`/[`OrchestratorCommand::AskAgent`]. Builder additif façon D3 :
-    /// signature de [`Self::new`] **inchangée** (les tests/call sites legacy restent
-    /// verts), le câblage fait `OrchestratorService::new(...).with_structured(reg)`.
+    /// Branche le **médiateur d'entrée** (cadrage C3 §5.2) pour servir
+    /// `agent.message`/[`OrchestratorCommand::AskAgent`] et
+    /// `agent.reply`/[`OrchestratorCommand::Reply`]. Le `mailbox` est le moteur de
+    /// corrélation **sous-jacent** au médiateur (le même `InMemoryMailbox` que
+    /// `MediatedInbox` enveloppe) : on l'injecte ensemble pour pouvoir `resolve`/
+    /// `resolve_ticket`/`cancel_head` un ticket. Builder additif : signature de
+    /// [`Self::new`] **inchangée** (les tests/call sites legacy restent verts).
     #[must_use]
-    pub fn with_structured(mut self, structured: Arc<StructuredSessions>) -> Self {
-        self.structured = Some(structured);
+    pub fn with_input_mediator(
+        mut self,
+        input: Arc<dyn InputMediator>,
+        mailbox: Arc<dyn domain::mailbox::AgentMailbox>,
+    ) -> Self {
+        self.input = Some(input);
+        self.mailbox = Some(mailbox);
+        self
+    }
+
+    /// Branche le [`ConversationRegistry`] (cadrage C3 §5.2) pour résoudre
+    /// paresseusement le fil `A↔B` (ou `User↔B`) d'un `ask` et séparer les contextes.
+    /// Builder additif (signature de [`Self::new`] inchangée).
+    #[must_use]
+    pub fn with_conversations(mut self, conversations: Arc<dyn ConversationRegistry>) -> Self {
+        self.conversations = Some(conversations);
         self
     }
 
@@ -175,6 +268,17 @@ impl OrchestratorService {
         self
     }
 
+    /// Branche le [`McpRuntimeProvider`] (app-tauri) pour que les (re)lancements
+    /// issus du chemin `ask` (`ensure_live_pty`) écrivent la déclaration MCP **réelle**
+    /// (endpoint + exe + requester) au lieu de la minimale — sans quoi le pont MCP
+    /// n'est jamais spawné et la cible ne peut pas appeler `idea_reply` (timeout).
+    /// Builder additif : signature de [`Self::new`] **inchangée**.
+    #[must_use]
+    pub fn with_mcp_runtime_provider(mut self, provider: Arc<dyn McpRuntimeProvider>) -> Self {
+        self.mcp_runtime_provider = Some(provider);
+        self
+    }
+
     /// Dispatches a validated command against `project`.
     ///
     /// # Errors
@@ -196,9 +300,16 @@ impl OrchestratorService {
                 self.spawn_agent(project, name, profile, context, visibility)
                     .await
             }
-            OrchestratorCommand::AskAgent { target, task } => {
-                self.ask_agent(project, target, task).await
-            }
+            OrchestratorCommand::AskAgent {
+                target,
+                task,
+                requester,
+            } => self.ask_agent(project, target, task, requester).await,
+            OrchestratorCommand::Reply {
+                from,
+                ticket,
+                result,
+            } => self.reply(from, ticket, result),
             OrchestratorCommand::ListAgents => self.list_agents(project).await,
             OrchestratorCommand::StopAgent { name } => self.stop_agent(project, name).await,
             OrchestratorCommand::UpdateAgentContext { name, context } => {
@@ -209,9 +320,135 @@ impl OrchestratorService {
                 content,
                 scope,
             } => self.create_skill(project, name, content, scope).await,
+            OrchestratorCommand::ReadContext { target, requester } => {
+                self.read_context(project, target, requester).await
+            }
+            OrchestratorCommand::ProposeContext {
+                target,
+                content,
+                requester,
+            } => self.propose_context(project, target, content, requester).await,
+            OrchestratorCommand::ReadMemory { slug, requester } => {
+                self.read_memory(project, slug, requester).await
+            }
+            OrchestratorCommand::WriteMemory {
+                slug,
+                content,
+                requester,
+            } => self.write_memory(project, slug, content, requester).await,
         }
     }
 
+    /// Returns the injected C7 use cases, or a typed error when unwired.
+    fn require_context_guard(&self) -> Result<&ContextGuardUseCases, AppError> {
+        self.context_guard.as_deref().ok_or_else(|| {
+            AppError::Invalid("FileGuard context/memory tools are not configured".to_owned())
+        })
+    }
+
+    /// `context.read` → reads an IdeA-owned context under a shared read-lease; the
+    /// body is returned inline in the outcome's `reply`.
+    async fn read_context(
+        &self,
+        project: &Project,
+        target: Option<String>,
+        requester: ConversationParty,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let md = self
+            .require_context_guard()?
+            .read_context
+            .execute(ReadContextInput {
+                project: project.clone(),
+                target: target.clone(),
+                requester,
+            })
+            .await?;
+        Ok(OrchestratorOutcome {
+            detail: format!(
+                "read {} context",
+                target.as_deref().unwrap_or("project")
+            ),
+            reply: Some(md.into_string()),
+        })
+    }
+
+    /// `context.propose` → direct write (agent ctx / orchestrator on global) or a
+    /// materialised proposal (non-orchestrator on global).
+    async fn propose_context(
+        &self,
+        project: &Project,
+        target: Option<String>,
+        content: String,
+        requester: ConversationParty,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let outcome = self
+            .require_context_guard()?
+            .propose_context
+            .execute(ProposeContextInput {
+                project: project.clone(),
+                target: target.clone(),
+                content,
+                requester,
+            })
+            .await?;
+        let detail = match outcome {
+            ProposeOutcome::Written => format!(
+                "wrote {} context",
+                target.as_deref().unwrap_or("project")
+            ),
+            ProposeOutcome::Proposed { path } => {
+                format!("filed proposal for project context at {path}")
+            }
+        };
+        Ok(OrchestratorOutcome { detail, reply: None })
+    }
+
+    /// `memory.read` → reads a note (or the index) under a shared read-lease; the
+    /// content is returned inline in the outcome's `reply`.
+    async fn read_memory(
+        &self,
+        project: &Project,
+        slug: Option<String>,
+        requester: ConversationParty,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let content = self
+            .require_context_guard()?
+            .read_memory
+            .execute(ReadMemoryInput {
+                project: project.clone(),
+                slug: slug.clone(),
+                requester,
+            })
+            .await?;
+        Ok(OrchestratorOutcome {
+            detail: format!("read memory {}", slug.as_deref().unwrap_or("index")),
+            reply: Some(content),
+        })
+    }
+
+    /// `memory.write` → writes a note under an exclusive write-lease.
+    async fn write_memory(
+        &self,
+        project: &Project,
+        slug: String,
+        content: String,
+        requester: ConversationParty,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        self.require_context_guard()?
+            .write_memory
+            .execute(WriteMemoryInput {
+                project: project.clone(),
+                slug: slug.clone(),
+                content,
+                requester,
+            })
+            .await?;
+        Ok(OrchestratorOutcome {
+            detail: format!("wrote memory {slug}"),
+            reply: None,
+        })
+    }
+
     /// `spawn_agent`: create the agent if the manifest doesn't already hold one by
     /// that name, then launch it (which publishes `AgentLaunched` → the UI opens a
     /// cell + the Agents tab).
@@ -328,88 +565,346 @@ impl OrchestratorService {
         })
     }
 
-    /// `agent.message`: the **synchronous inter-agent rendezvous** (§17.4).
+    /// `agent.message` / `idea_ask_agent`: the **inter-agent delegation rendezvous**
+    /// (Option 1 « Terminal + MCP », lot B-3).
     ///
-    /// Resolves the target by name, ensures it has a **live structured session**
-    /// (launching it in structured mode if needed), sends `task` and **waits for the
-    /// turn's `Final`** via [`send_blocking`], then returns its content as
-    /// [`OrchestratorOutcome::reply`] and publishes [`DomainEvent::AgentReplied`].
+    /// The target's human-facing view is now a **raw native terminal** (PTY REPL), and
+    /// delegation flows through the terminal's single FIFO input plus the MCP mailbox:
     ///
-    /// Invariants:
-    /// - **1 session vivante/agent** : on réutilise la session structurée vivante si
-    ///   elle existe ; sinon `LaunchAgent` (gardé sur les deux registres) la crée.
-    /// - **Timeout ne tue pas la session** : [`send_blocking`] remonte
-    ///   [`AppError::Process`] (via [`domain::ports::AgentSessionError::Timeout`]) en
-    ///   laissant la session vivante dans le registre (retry possible).
-    /// - **Cible PTY-only** (profil sans `structured_adapter`, ou agent déjà vivant en
-    ///   PTY) ⇒ [`AppError::Invalid`] explicite, **jamais** un ACK trompeur.
+    /// 1. Resolve the target by name and acquire its **per-agent turn lock** so two
+    ///    `ask`s for the same target serialise FIFO (1 agent = 1 employee).
+    /// 2. Ensure the target is **live in the PTY registry** — reusing its terminal if
+    ///    it is already running, otherwise launching it in the background (a normal
+    ///    PTH launch: a live PTY *is* the channel now, not an error as before).
+    /// 3. **Enqueue a ticket** in the [`AgentMailbox`] (registering the reply slot)
+    ///    **then write** the task into the target's terminal, prefixed with the asking
+    ///    agent + ticket id so the target knows to answer via `idea_reply`.
+    /// 4. **Await** the [`domain::mailbox::PendingReply`] bounded by [`ASK_AGENT_TIMEOUT`]:
+    ///    the target's later `idea_reply(result)` lands in [`Self::reply`] →
+    ///    `mailbox.resolve`, waking this await. On timeout the ticket is retired from
+    ///    the head ([`AgentMailbox::cancel_head`]) — **the target stays alive** — and a
+    ///    typed timeout is returned (retry possible).
+    /// 5. Return the reply as [`OrchestratorOutcome::reply`] and publish
+    ///    [`DomainEvent::AgentReplied`].
     ///
     /// # Errors
-    /// - [`AppError::NotFound`] si l'agent cible est inconnu ;
-    /// - [`AppError::Invalid`] si la messagerie structurée n'est pas câblée, ou si la
-    ///   cible n'est pas pilotable en mode structuré ;
-    /// - [`AppError::Process`] sur échec/timeout du tour structuré.
+    /// - [`AppError::NotFound`] if the target agent is unknown;
+    /// - [`AppError::Invalid`] if the mailbox/PTY channel is not wired;
+    /// - [`AppError::Process`] on a launch/PTY-write failure, or on the await timeout
+    ///   (turn timeout *or* queue-wait timeout — same typed error).
     async fn ask_agent(
         &self,
         project: &Project,
         target: String,
         task: String,
+        requester: Option<AgentId>,
     ) -> Result<OrchestratorOutcome, AppError> {
-        let structured = self.structured.as_ref().ok_or_else(|| {
-            AppError::Invalid(
-                "la messagerie inter-agents (agent.message) n'est pas disponible : \
-                 registre des sessions structurées non câblé"
-                    .to_owned(),
-            )
-        })?;
+        let (input, mailbox) = match (&self.input, &self.mailbox) {
+            (Some(i), Some(m)) => (i, m),
+            _ => {
+                return Err(AppError::Invalid(
+                    "la messagerie inter-agents (idea_ask_agent) n'est pas disponible : \
+                     médiateur d'entrée non câblé"
+                        .to_owned(),
+                ))
+            }
+        };
 
-        let agent_id = self
-            .find_agent_id_by_name(project, &target)
+        let agent = self
+            .find_agent_by_name(project, &target)
             .await?
             .ok_or_else(|| AppError::NotFound(format!("agent {target}")))?;
+        let agent_id = agent.id;
 
-        // Sérialisation FIFO **par agent** (A0, cadrage v5 §4) : on acquiert le verrou
-        // de tour de la **cible** avant tout `send_blocking`, et on le tient pour TOUT
-        // le tour réel (rendez-vous direct *ou* lancement-puis-envoi sur cible morte).
-        // Le garde `_turn` est RAII : il tombe en fin de portée, y compris sur chaque
-        // early-return d'erreur ci-dessous ⇒ le tour suivant en file démarre alors.
-        //
-        // Verrou par `agent_id` ⇒ un `ask` vers A et un vers B ne se bloquent jamais ;
-        // un seul verrou tenu (celui de la cible) ⇒ pas d'inter-verrouillage/deadlock.
-        // Le timeout de TOUR ([`ASK_AGENT_TIMEOUT`]) borne `send_blocking`, **pas**
-        // l'attente du verrou ; cette attente a son **propre** plafond
-        // ([`ASK_QUEUE_WAIT_CAP`]) pour éviter l'inanition.
+        // F2 — garde profil : refuser **immédiatement** une cible dont le profil ne
+        // sait pas consommer le pont `idea_*` matérialisé via `.mcp.json`, plutôt que
+        // de laisser le round-trip échouer en timeout muet (300s).
+        self.guard_mcp_bridge_supported(&agent.profile_id, &target)
+            .await?;
+
+        // Détection de cycle (cadrage C3 §6) : si l'ask vient d'un **agent** A vers la
+        // cible B, refuser AVANT tout enqueue si poser l'arête A→B fermerait un cycle
+        // d'attente (B attend déjà …→A). Pur, sans I/O ⇒ jamais de deadlock.
+        if let Some(from) = requester {
+            let cycles = {
+                let g = self
+                    .wait_for
+                    .lock()
+                    .unwrap_or_else(std::sync::PoisonError::into_inner);
+                g.would_cycle(from, agent_id)
+            };
+            if cycles {
+                return Err(AppError::Invalid(format!(
+                    "délégation ré-entrante refusée : demander à l'agent '{target}' créerait \
+                     un cycle d'attente inter-agents (deadlock évité)"
+                )));
+            }
+        }
+
+        // Résoudre paresseusement le **fil** de l'ask : A↔B si un agent demande, sinon
+        // User↔B. La session vivante est désormais keyée par conversation (lève
+        // `session-registry-agent-ambiguity`).
+        let conversation_id = self.resolve_conversation(requester, agent_id);
+
+        // Sérialisation FIFO **par agent** (A0) : verrou de tour de la **cible**, tenu
+        // pour TOUT le tour (enqueue → réponse). RAII : tombe sur chaque early-return.
         let lock = self.ask_lock_for(&agent_id);
         let _turn = match tokio::time::timeout(ASK_QUEUE_WAIT_CAP, lock.lock_owned()).await {
             Ok(guard) => guard,
             Err(_elapsed) => {
-                // Réutilise le **même** type de timeout que le tour (cadrage v5 §4) :
-                // `AgentSessionError::Timeout` ⇒ `AppError::Process`.
-                return Err(AppError::from(
-                    domain::ports::AgentSessionError::Timeout,
-                ));
+                return Err(AppError::from(domain::ports::AgentSessionError::Timeout));
             }
         };
 
-        // 1. Session structurée déjà vivante ? ⇒ rendez-vous direct.
-        if let Some(session) = structured.session_for_agent(&agent_id) {
-            let content = send_blocking(session.as_ref(), &task, Some(ASK_AGENT_TIMEOUT)).await?;
-            return Ok(self.reply_outcome(agent_id, &target, content));
+        // Poser l'arête d'attente A→B (retirée en fin de tour par le RAII `_edge`).
+        let _edge = requester.map(|from| WaitEdgeGuard::new(self, from, agent_id));
+
+        // 1. Garantir la cible vivante en PTY pour CE fil ; lier sa session à la
+        //    conversation, et brancher son handle d'entrée sur le médiateur (livraison).
+        let handle = self
+            .ensure_live_pty(project, agent_id, conversation_id, &target)
+            .await?;
+        // Arm prompt-ready detection (C5) with the target profile's literal marker, so a
+        // return-to-prompt frees the turn (the other OR signal being `idea_reply`).
+        let prompt_pattern = self.prompt_pattern_for_agent(project, agent_id).await;
+        input.bind_handle_with_prompt(agent_id, handle.clone(), prompt_pattern);
+
+        // 2. Enregistrer le ticket (slot de réponse) + livrer le tour via le médiateur
+        //    (écriture sérialisée dans le PTY — plus d'écriture ad hoc ici). Le ticket
+        //    porte la source (Human/Agent) et la conversation cible.
+        let requester_label = self.requester_label(project, requester).await;
+        let ticket_id = TicketId::new_random();
+        let ticket = match requester {
+            Some(from) => {
+                Ticket::from_agent(ticket_id, from, conversation_id, requester_label, task)
+            }
+            None => Ticket::from_human(ticket_id, conversation_id, requester_label, task),
+        };
+        let pending = input.enqueue(agent_id, ticket);
+        // Delivery is the mediator's responsibility (`InputMediator::enqueue` writes the
+        // turn into the bound handle). The service no longer writes the PTY directly —
+        // no ad-hoc `[IdeA · tâche …]` line here, no `\r` band-aid (cadrage C3 §5.1).
+
+        // 3. Attendre la réponse, bornée. Timeout/canal fermé ⇒ retirer le ticket
+        //    (cible laissée vivante) et renvoyer une erreur typée.
+        match tokio::time::timeout(ASK_AGENT_TIMEOUT, pending).await {
+            Ok(Ok(result)) => Ok(self.reply_outcome(agent_id, &target, result)),
+            Ok(Err(_cancelled)) => {
+                mailbox.cancel_head(agent_id, ticket_id);
+                Err(AppError::Process(format!(
+                    "agent {target} : canal de réponse fermé avant un résultat"
+                )))
+            }
+            Err(_elapsed) => {
+                mailbox.cancel_head(agent_id, ticket_id);
+                Err(AppError::from(domain::ports::AgentSessionError::Timeout))
+            }
+        }
+    }
+
+    /// `SubmitHumanInput` (cadrage C4 §5.3) — the **human** Envoyer path.
+    ///
+    /// The operator types into IdeA's mediated input; this resolves the `User↔Agent`
+    /// thread, ensures the target is live in the PTY registry, binds its handle on the
+    /// mediator, and **enqueues** a `Ticket::from_human` into the **same FIFO** the
+    /// inter-agent delegations use (`InputMediator::enqueue`) — so a human submit and a
+    /// delegation serialise on the same agent («1 agent = 1 employee»).
+    ///
+    /// Unlike [`Self::ask_agent`], it is **fire-and-forget**: the human watches the
+    /// terminal for the answer, so we do **not** await the [`PendingReply`] (the reply
+    /// slot is registered and simply left to resolve/expire on its own). The busy
+    /// event is emitted at the mediator's source (Idle→Busy on the starting enqueue).
+    ///
+    /// # Errors
+    /// - [`AppError::Invalid`] if the input mediator is not wired;
+    /// - [`AppError::NotFound`] if the target agent is unknown;
+    /// - [`AppError::Process`] on a launch/PTY failure while ensuring the live session.
+    pub async fn submit_human_input(
+        &self,
+        project: &Project,
+        agent_id: AgentId,
+        text: String,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let input = self.input.as_ref().ok_or_else(|| {
+            AppError::Invalid(
+                "l'entrée médiée (submit_agent_input) n'est pas disponible : \
+                 médiateur d'entrée non câblé"
+                    .to_owned(),
+            )
+        })?;
+
+        // Display label for error/launch messages; the agent must exist in the
+        // manifest. A human submit to an unknown id is a NotFound, never a panic.
+        let target = self
+            .find_name_by_agent_id(project, agent_id)
+            .await
+            .ok_or_else(|| AppError::NotFound(format!("agent {agent_id}")))?;
+        let target = target.as_str();
+
+        // User↔Agent thread (no requester ⇒ left = User). Same lazy resolution as ask.
+        let conversation_id = self.resolve_conversation(None, agent_id);
+
+        // Ensure the target is live for this thread and bind its input handle on the
+        // mediator (delivery path). Same call the ask path uses.
+        let handle = self
+            .ensure_live_pty(project, agent_id, conversation_id, target)
+            .await?;
+        let prompt_pattern = self.prompt_pattern_for_agent(project, agent_id).await;
+        input.bind_handle_with_prompt(agent_id, handle, prompt_pattern);
+
+        // Enqueue a human-sourced ticket in the SAME FIFO as delegations. Fire-and-
+        // forget: we drop the PendingReply (the human reads the terminal). The
+        // mediator emits AgentBusyChanged at the source on a starting turn.
+        let ticket = Ticket::from_human(TicketId::new_random(), conversation_id, "vous", text);
+        let _pending = input.enqueue(agent_id, ticket);
+
+        Ok(OrchestratorOutcome {
+            detail: format!("submitted human input to agent {target}"),
+            reply: None,
+        })
+    }
+
+    /// Interrupt (cadrage C4 §5.3) — the **Interrompre** path (Échap/stop).
+    ///
+    /// Resolves the target by name and calls [`InputMediator::preempt`], which signals
+    /// the running turn to stop (best-effort interrupt byte to the agent's bound PTY
+    /// handle). It is **not** an enqueue and resolves **no** ticket — a pending caller
+    /// is never silently answered. Idempotent: interrupting an idle agent is a no-op.
+    ///
+    /// # Errors
+    /// - [`AppError::Invalid`] if the input mediator is not wired;
+    /// - [`AppError::NotFound`] if the target agent is unknown.
+    pub async fn interrupt_agent(
+        &self,
+        project: &Project,
+        agent_id: AgentId,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let input = self.input.as_ref().ok_or_else(|| {
+            AppError::Invalid(
+                "l'interruption (interrupt_agent) n'est pas disponible : \
+                 médiateur d'entrée non câblé"
+                    .to_owned(),
+            )
+        })?;
+
+        // Confirm the agent exists (typed NotFound rather than a silent no-op on a
+        // bogus id). The manifest lookup also keeps the contract symmetric with submit.
+        if self
+            .find_name_by_agent_id(project, agent_id)
+            .await
+            .is_none()
+        {
+            return Err(AppError::NotFound(format!("agent {agent_id}")));
         }
 
-        // 2. Pas de session structurée. Si l'agent est vivant en **PTY** (terminal
-        //    brut), il n'est pas adressable en `ask` ⇒ erreur typée explicite (pas
-        //    d'ACK « launched »).
-        if self.sessions.session_for_agent(&agent_id).is_some() {
-            return Err(AppError::Invalid(format!(
-                "agent {target} n'est pas pilotable en mode structuré \
-                 (session terminal brut, pas de canal de réponse)"
-            )));
+        input.preempt(agent_id);
+
+        Ok(OrchestratorOutcome {
+            detail: format!("interrupted agent {agent_id}"),
+            reply: None,
+        })
+    }
+
+    /// Resolves the conversation thread id for an ask: `A↔B` when an agent requests,
+    /// else `User↔B` (cadrage C3 §5.2). Without a wired registry, falls back to a
+    /// stable per-agent id derived from the target (legacy routing — never panics).
+    fn resolve_conversation(
+        &self,
+        requester: Option<AgentId>,
+        target: AgentId,
+    ) -> domain::conversation::ConversationId {
+        let left = match requester {
+            Some(from) => ConversationParty::agent(from),
+            None => ConversationParty::User,
+        };
+        let right = ConversationParty::agent(target);
+        match &self.conversations {
+            Some(reg) => reg.resolve(left, right).id,
+            None => domain::conversation::ConversationId::from_uuid(target.as_uuid()),
+        }
+    }
+
+
+    /// `agent.reply` / `idea_reply`: the target agent renders the result of the task
+    /// it is currently processing (Option 1, lot B-4).
+    ///
+    /// Positional correlation: `from` is the **emitting** agent (its identity comes
+    /// from the MCP handshake, not from a model-managed id), so the result resolves
+    /// the ticket at the **head** of *that agent's* mailbox queue — the task it is
+    /// working on. ACK only: no inline payload, no `AgentReplied` here (that belongs
+    /// to the asking side's `ask_agent`).
+    ///
+    /// # Errors
+    /// - [`AppError::Invalid`] if the mailbox is not wired;
+    /// - [`AppError::Invalid`] if `from` has no in-flight request (a reply with no
+    ///   matching ask) — typed, never a panic.
+    fn reply(
+        &self,
+        from: AgentId,
+        ticket: Option<TicketId>,
+        result: String,
+    ) -> Result<OrchestratorOutcome, AppError> {
+        let mailbox = self.mailbox.as_ref().ok_or_else(|| {
+            AppError::Invalid(
+                "idea_reply n'est pas disponible : file inter-agents non câblée".to_owned(),
+            )
+        })?;
+        // Corrélation par ticket quand l'agent l'a renvoyé (déterministe, multi-fil) ;
+        // sinon repli sur la tête de file de l'émetteur (compat agents mono-fil).
+        match ticket {
+            Some(ticket_id) => mailbox.resolve_ticket(from, ticket_id, result),
+            None => mailbox.resolve(from, result),
+        }
+        .map_err(|e| AppError::Invalid(e.to_string()))?;
+        // Explicit «end-of-turn» signal (cadrage §6, lot C5): an `idea_reply` means the
+        // emitting agent `from` finished its delegated task ⇒ mark it Idle so its FIFO
+        // advances to the next queued ticket. This is the deterministic OR signal that
+        // pairs with prompt-ready detection; whichever fires first frees the turn. No-op
+        // (and no spurious event) when the mediator is absent or `from` was already idle.
+        if let Some(input) = self.input.as_ref() {
+            input.mark_idle(from);
+        }
+        Ok(OrchestratorOutcome {
+            detail: format!("reply from agent {from} delivered"),
+            reply: None,
+        })
+    }
+
+    /// Ensures the target agent has a **live PTY session**, returning its handle.
+    ///
+    /// Reuses the running terminal when present; otherwise launches the agent in the
+    /// background (a normal PTH launch — a live PTY is the delegation channel). After
+    /// a launch the handle is resolved from the registry; a missing handle is a
+    /// [`AppError::Process`] (the launch did not register a PTY session, e.g. a profile
+    /// IdeA cannot drive as a terminal).
+    async fn ensure_live_pty(
+        &self,
+        project: &Project,
+        agent_id: AgentId,
+        conversation_id: domain::conversation::ConversationId,
+        target: &str,
+    ) -> Result<PtyHandle, AppError> {
+        // «1 session vivante / conversation» (cadrage C3 §5.2) : on cherche d'abord la
+        // session du **fil**, puis on retombe sur la session de l'agent (compat : un
+        // agent mono-fil dont la session n'a pas encore été liée à sa conversation).
+        let existing = self
+            .sessions
+            .session_for(conversation_id)
+            .or_else(|| self.sessions.session_for_agent(&agent_id));
+        if let Some(session_id) = existing {
+            if let Some(handle) = self.sessions.handle(&session_id) {
+                // (Re)lier le fil à cette session vivante (idempotent).
+                self.bind_conversation_session(conversation_id, session_id);
+                return Ok(handle);
+            }
         }
 
-        // 3. Cible morte : on la lance en mode structuré (background) puis on envoie.
-        let launched = self
-            .launch_agent
+        // Dead target: launch it in the background (PTY). On injecte ici la déclaration
+        // MCP **réelle** via le [`McpRuntimeProvider`] câblé (app-tauri détient l'exe et
+        // l'endpoint) — c'est ce qui permet au pont MCP de la cible de se spawner et donc
+        // à la cible d'appeler `idea_reply`. Provider absent (ou `runtime_for` → `None`)
+        // ⇒ déclaration minimale comme avant (dégradation gracieuse).
+        self.launch_agent
             .execute(LaunchAgentInput {
                 project: project.clone(),
                 agent_id,
@@ -417,30 +912,71 @@ impl OrchestratorService {
                 cols: DEFAULT_COLS,
                 node_id: None,
                 conversation_id: None,
-                // ask_agent revival launch (inside `application`): MCP runtime not
-                // injected here (see the `spawn_agent` note above).
-                mcp_runtime: None,
+                mcp_runtime: self
+                    .mcp_runtime_provider
+                    .as_ref()
+                    .and_then(|p| p.runtime_for(project, agent_id)),
             })
             .await?;
 
-        // Si le lancement n'a pas produit de session structurée, le profil de la cible
-        // est PTY-only (pas de `structured_adapter`) ⇒ non adressable en `ask`.
-        if launched.structured.is_none() {
-            return Err(AppError::Invalid(format!(
-                "agent {target} n'est pas pilotable en mode structuré \
-                 (profil sans adaptateur structuré)"
-            )));
-        }
+        let session_id = self
+            .sessions
+            .session_for_agent(&agent_id)
+            .ok_or_else(|| {
+                AppError::Process(format!(
+                    "agent {target} n'a pas de session terminal vivante après lancement"
+                ))
+            })?;
+        // Lier la session fraîchement lancée à CE fil (registre terminal + registre de
+        // conversations) ⇒ un prochain ask sur le même fil la réutilise.
+        self.bind_conversation_session(conversation_id, session_id);
+        self.sessions.handle(&session_id).ok_or_else(|| {
+            AppError::Process(format!("handle PTY de l'agent {target} introuvable après lancement"))
+        })
+    }
 
-        // La session vient d'être enregistrée par LaunchAgent : on la récupère par
-        // agent (invariant « 1 session/agent » ⇒ non ambigu).
-        let session = structured.session_for_agent(&agent_id).ok_or_else(|| {
-            AppError::Process(format!(
-                "session structurée de l'agent {target} introuvable après lancement"
-            ))
-        })?;
-        let content = send_blocking(session.as_ref(), &task, Some(ASK_AGENT_TIMEOUT)).await?;
-        Ok(self.reply_outcome(agent_id, &target, content))
+    /// Binds `conversation` to `session` in both the terminal registry (fast
+    /// `session_for`) and the [`ConversationRegistry`] (domain thread state), when the
+    /// latter is wired. Idempotent.
+    fn bind_conversation_session(
+        &self,
+        conversation: domain::conversation::ConversationId,
+        session: domain::SessionId,
+    ) {
+        self.sessions.bind_conversation(conversation, session);
+        if let Some(reg) = &self.conversations {
+            reg.bind_session(conversation, SessionRef::new(session));
+        }
+    }
+
+    /// Resolves a human-friendly label for the **requesting** agent to prefix the
+    /// delegated task with. Best-effort: there is no requester id threaded into
+    /// [`OrchestratorCommand::AskAgent`] today, so this falls back to a stable
+    /// `"un autre agent"` label. Kept as a seam so a future requester-aware ask can
+    /// surface the real name without touching the call sites.
+    async fn requester_label(&self, project: &Project, requester: Option<AgentId>) -> String {
+        match requester {
+            None => "un autre agent".to_owned(),
+            Some(from) => self
+                .find_name_by_agent_id(project, from)
+                .await
+                .unwrap_or_else(|| "un autre agent".to_owned()),
+        }
+    }
+
+    /// Best-effort display name for an agent id (manifest lookup). `None` when the id
+    /// is unknown — the caller falls back to a generic label.
+    async fn find_name_by_agent_id(&self, project: &Project, id: AgentId) -> Option<String> {
+        self.list_agents
+            .execute(ListAgentsInput {
+                project: project.clone(),
+            })
+            .await
+            .ok()?
+            .agents
+            .into_iter()
+            .find(|a| a.id == id)
+            .map(|a| a.name)
     }
 
     /// Builds the success outcome of an `ask` and publishes [`DomainEvent::AgentReplied`]
@@ -590,6 +1126,104 @@ impl OrchestratorService {
             .map(|a| a.id))
     }
 
+    /// Finds the full [`domain::Agent`] by display name (case-insensitive) in the
+    /// project manifest. Variante de [`Self::find_agent_id_by_name`] qui conserve
+    /// l'agent entier (notamment son `profile_id`), nécessaire à la garde F2.
+    async fn find_agent_by_name(
+        &self,
+        project: &Project,
+        name: &str,
+    ) -> Result<Option<domain::Agent>, AppError> {
+        let listed = self
+            .list_agents
+            .execute(ListAgentsInput {
+                project: project.clone(),
+            })
+            .await?;
+        Ok(listed
+            .agents
+            .into_iter()
+            .find(|a| a.name.eq_ignore_ascii_case(name)))
+    }
+
+    /// Garde F2 : vérifie que le profil de la cible **sait consommer** le pont
+    /// `idea_*` matérialisé par IdeA, et renvoie sinon une [`AppError::Invalid`]
+    /// **immédiate** (au lieu d'un timeout 300s muet sur le round-trip).
+    ///
+    /// **Critère retenu** (le plus robuste aujourd'hui) : le pont est honoré ssi le
+    /// profil porte une capacité MCP en stratégie `ConfigFile` ciblant `.mcp.json`
+    /// **ET** que son adaptateur structuré est `Claude`. En effet IdeA matérialise le
+    /// serveur MCP sous forme d'un fichier `.mcp.json` dans le run dir, ce que **seul**
+    /// Claude Code lit réellement ; Codex déclare pourtant la même stratégie
+    /// `ConfigFile(.mcp.json)` mais lit en pratique `~/.codex/config.toml` ⇒ le pont
+    /// n'est jamais branché et la cible ne peut pas appeler `idea_reply`. On exige donc
+    /// l'adaptateur `Claude` plutôt qu'une simple présence de capacité MCP, ce qui
+    /// exclut Codex de fait et reste valable pour tout futur profil non-Claude.
+    ///
+    /// Profil introuvable ⇒ on **n'interdit pas** (laisse le flux suivre son cours
+    /// comme avant) : la garde ne fait que transformer un échec connu en erreur typée.
+    async fn guard_mcp_bridge_supported(
+        &self,
+        profile_id: &ProfileId,
+        target: &str,
+    ) -> Result<(), AppError> {
+        use domain::profile::{McpConfigStrategy, StructuredAdapter};
+
+        let Some(profile) = self
+            .profiles
+            .list()
+            .await?
+            .into_iter()
+            .find(|p| &p.id == profile_id)
+        else {
+            return Ok(());
+        };
+
+        let honours_mcp_json = matches!(
+            profile.mcp.as_ref().map(|c| &c.config),
+            Some(McpConfigStrategy::ConfigFile { target }) if target == ".mcp.json"
+        );
+        let is_claude = profile.structured_adapter == Some(StructuredAdapter::Claude);
+
+        if honours_mcp_json && is_claude {
+            return Ok(());
+        }
+
+        Err(AppError::Invalid(format!(
+            "la cible '{target}' (profil '{}', adaptateur {:?}) ne supporte pas encore le \
+             pont idea_* : la délégation inter-agents passe par un serveur MCP déclaré en \
+             .mcp.json, que seul un profil Claude consomme aujourd'hui. Cible un agent au \
+             profil Claude.",
+            profile.name, profile.structured_adapter
+        )))
+    }
+
+    /// Resolves the **prompt-ready pattern** (cadrage §6, lot C5) of the agent's
+    /// profile, used to arm the [`InputMediator`]'s prompt detection at `bind_handle`
+    /// time. Returns `None` when the agent, its profile, or the pattern is absent —
+    /// the safe fallback: no pattern ⇒ Idle only via explicit signal/timeout.
+    async fn prompt_pattern_for_agent(
+        &self,
+        project: &Project,
+        agent_id: AgentId,
+    ) -> Option<String> {
+        let agent = self
+            .list_agents
+            .execute(ListAgentsInput {
+                project: project.clone(),
+            })
+            .await
+            .ok()?
+            .agents
+            .into_iter()
+            .find(|a| a.id == agent_id)?;
+        let profiles = self.profiles.list().await.ok()?;
+        profiles
+            .into_iter()
+            .find(|p| p.id == agent.profile_id)
+            .and_then(|p| p.prompt_ready_pattern)
+    }
+
     /// Resolves a human-friendly profile reference (slug like `claude-code`,
     /// command like `claude`, or display name like `Claude Code`) to a configured
     /// [`ProfileId`]. Matching is universal — never hard-coded to one AI — by
@@ -612,6 +1246,44 @@ impl OrchestratorService {
     }
 }
 
+/// RAII guard that posts a wait-for edge `from → to` for the duration of an ask and
+/// removes it on drop (reply, timeout, or any early return) — the same discipline as
+/// the per-agent turn lock. Holds a raw pointer-free borrow via the shared mutex on
+/// the service's [`WaitForGraph`]; constructed only inside `ask_agent` where the
+/// service outlives the guard.
+struct WaitEdgeGuard<'a> {
+    graph: &'a StdMutex<WaitForGraph>,
+    from: AgentId,
+    to: AgentId,
+}
+
+impl<'a> WaitEdgeGuard<'a> {
+    fn new(service: &'a OrchestratorService, from: AgentId, to: AgentId) -> Self {
+        {
+            let mut g = service
+                .wait_for
+                .lock()
+                .unwrap_or_else(std::sync::PoisonError::into_inner);
+            g.add_edge(from, to);
+        }
+        Self {
+            graph: &service.wait_for,
+            from,
+            to,
+        }
+    }
+}
+
+impl Drop for WaitEdgeGuard<'_> {
+    fn drop(&mut self) {
+        let mut g = self
+            .graph
+            .lock()
+            .unwrap_or_else(std::sync::PoisonError::into_inner);
+        g.remove_edge(self.from, self.to);
+    }
+}
+
 /// Normalises a profile reference for tolerant matching: lowercased, with spaces,
 /// dashes and underscores stripped (`"Claude Code"`, `"claude-code"`, `"claude"`
 /// → comparable forms; `claude` ⊂ ... handled by the command match above).

crates/application/src/terminal/registry.rs

@@ -9,6 +9,7 @@
 use std::collections::HashMap;
 use std::sync::{Arc, Mutex};
 
+use domain::conversation::ConversationId;
 use domain::ports::{AgentSession, PtyHandle};
 use domain::{AgentId, NodeId, SessionId, SessionKind, TerminalSession};
 
@@ -44,6 +45,11 @@ pub trait LiveAgentRegistry: Send + Sync {
 #[derive(Default)]
 pub struct TerminalSessions {
     entries: Mutex<HashMap<SessionId, Entry>>,
+    /// Conversation → live session binding (cadrage C3 §5.2): «1 session vivante /
+    /// **conversation**» (remplace «1 / agent»). Populated by the orchestrator when an
+    /// ask resolves/launches the session for a given thread. Separate from `entries`
+    /// (the domain [`TerminalSession`] does not carry a conversation id).
+    conversations: Mutex<HashMap<ConversationId, SessionId>>,
 }
 
 impl LiveAgentRegistry for TerminalSessions {
@@ -65,9 +71,50 @@ impl TerminalSessions {
     pub fn new() -> Self {
         Self {
             entries: Mutex::new(HashMap::new()),
+            conversations: Mutex::new(HashMap::new()),
         }
     }
 
+    /// Binds `conversation` to the live `session` (cadrage C3 §5.2). Idempotent:
+    /// re-binding the same conversation overwrites the target session.
+    pub fn bind_conversation(&self, conversation: ConversationId, session: SessionId) {
+        if let Ok(mut m) = self.conversations.lock() {
+            m.insert(conversation, session);
+        }
+    }
+
+    /// Returns the live [`SessionId`] bound to `conversation`, if any **and** still
+    /// registered (a stale binding to a closed session resolves to `None`).
+    ///
+    /// «1 session vivante / conversation» — deterministic, replacing the ambiguous
+    /// per-agent lookup for the orchestrator's ask path.
+    #[must_use]
+    pub fn session_for(&self, conversation: ConversationId) -> Option<SessionId> {
+        let sid = self.conversations.lock().ok()?.get(&conversation).copied()?;
+        // Only return it if the session is still live in `entries`.
+        self.entries
+            .lock()
+            .ok()
+            .filter(|m| m.contains_key(&sid))
+            .map(|_| sid)
+    }
+
+    /// Lists every live [`SessionId`] hosting `agent_id` (cadrage C3 §1.2 — an agent
+    /// may take part in several threads, so this is the **plural** of
+    /// [`Self::session_for_agent`]).
+    #[must_use]
+    pub fn sessions_for_agent(&self, agent_id: &AgentId) -> Vec<SessionId> {
+        self.entries
+            .lock()
+            .map(|m| {
+                m.values()
+                    .filter(|e| matches!(e.session.kind, SessionKind::Agent { agent_id: a } if &a == agent_id))
+                    .map(|e| e.session.id)
+                    .collect()
+            })
+            .unwrap_or_default()
+    }
+
     /// Inserts a freshly-opened session.
     pub fn insert(&self, handle: PtyHandle, session: TerminalSession) {
         if let Ok(mut map) = self.entries.lock() {
@@ -184,8 +231,12 @@ impl TerminalSessions {
             .unwrap_or_default()
     }
 
-    /// Removes a session from the registry, returning its handle if present.
+    /// Removes a session from the registry, returning its handle if present. Also
+    /// drops any conversation binding pointing at it (no stale `session_for`).
     pub fn remove(&self, id: &SessionId) -> Option<PtyHandle> {
+        if let Ok(mut c) = self.conversations.lock() {
+            c.retain(|_, sid| sid != id);
+        }
         self.entries
             .lock()
             .ok()

crates/application/tests/agent_lifecycle.rs

@@ -1312,11 +1312,11 @@ async fn launch_conventionfile_injects_project_memory_in_order() {
         "memory section present: {doc}"
     );
     assert!(
-        doc.contains("- [Git optionnel](git-optional.md) — git reste un simple tool (project)"),
+        doc.contains("- [Git optionnel](.ideai/memory/git-optional.md) — git reste un simple tool (project)"),
         "first memory line exact format: {doc}"
     );
     assert!(
-        doc.contains("- [Permissions](perm-archi.md) — sandbox OS + résumé injecté (reference)"),
+        doc.contains("- [Permissions](.ideai/memory/perm-archi.md) — sandbox OS + résumé injecté (reference)"),
         "second memory line exact format: {doc}"
     );
     // Recalled order preserved; section after the persona.