fix(agent): timeout MCP OpenCode aligné sur le plafond du rendez-vous (#95)

Le timeout hardcoded 15000ms (15s) dans le bloc mcp.idea de l'opencode.json
généré par IdeA était far too short pour idea_ask_agent, qui bloque pendant
que l'agent cible travaille. OpenCode tuait la requête à 15s avec l'erreur
-32001 « Request timed out », même si la cible répondait correctement
(visible dans le workstate). Claude/Codex n'étaient pas affectés car leur
config MCP n'a pas de champ timeout.

Désormais le timeout est résolu par resolve_opencode_mcp_timeout_ms() :
- défaut 4h (14_400_000 ms), aligné sur DEFAULT_RENDEZVOUS_CEILING ;
- overridable via IDEA_OPENCODE_MCP_TIMEOUT_MS ;
- fallback sûr sur 0/parse-error (jamais d'expiration instantanée).

Les 4 occurrences (lifecycle.rs x2 + assistant/mod.rs x2) utilisent la même
fonction exportée depuis application::agent. Aucune modification des configs
MCP Claude/Codex.

crates/application/src/agent/lifecycle.rs

@@ -2645,6 +2645,31 @@ fn mcp_server_wiring(
 ///
 /// The MCP server is named `idea`; OpenCode therefore exposes IdeA tools as
 /// `idea_idea_*` (`<serverName>_<toolName>`), matching the observed contract.
+/// Default MCP request timeout (milliseconds) injected into the OpenCode agent
+/// config (`opencode.json` → `mcp.idea.timeout`). OpenCode applies this **per
+/// `tools/call`** to its MCP servers; the original hardcoded `15_000` (15 s) was
+/// far too short for `idea_ask_agent`, which blocks while the target agent works
+/// (potentially minutes). Aligning on the rendezvous ceiling (4 h) ensures
+/// OpenCode's client never kills an in-flight delegation before the server-side
+/// watchdog resolves.
+///
+/// **Must stay ≥ `DEFAULT_RENDEZVOUS_CEILING`** so the MCP client timeout and the
+/// server-side absolute ceiling expire together — never the client first.
+/// Overridable via `IDEA_OPENCODE_MCP_TIMEOUT_MS`.
+pub const DEFAULT_OPENCODE_MCP_TIMEOUT_MS: u64 = 4 * 60 * 60 * 1000;
+
+/// Resolves the effective OpenCode MCP request timeout (ms) from the
+/// `IDEA_OPENCODE_MCP_TIMEOUT_MS` env var, falling back to
+/// [`DEFAULT_OPENCODE_MCP_TIMEOUT_MS`]. Parse failure or `0` ⇒ default, so a
+/// misconfigured value never collapses the timeout to an instant kill.
+pub fn resolve_opencode_mcp_timeout_ms() -> u64 {
+    std::env::var("IDEA_OPENCODE_MCP_TIMEOUT_MS")
+        .ok()
+        .and_then(|v| v.trim().parse::<u64>().ok())
+        .filter(|&ms| ms > 0)
+        .unwrap_or(DEFAULT_OPENCODE_MCP_TIMEOUT_MS)
+}
+
 fn opencode_config_json(
     config: &domain::profile::OpenCodeConfig,
     project_root: &str,
@@ -2725,7 +2750,7 @@ fn opencode_config_json(
                 "command": command_array,
                 "cwd": project_root,
                 "enabled": true,
-                "timeout": 15000
+                "timeout": resolve_opencode_mcp_timeout_ms()
             }
         }),
     );
@@ -2808,7 +2833,7 @@ fn opencode_provider_config_json(
                 "command": command_array,
                 "cwd": project_root,
                 "enabled": true,
-                "timeout": 15000
+                "timeout": resolve_opencode_mcp_timeout_ms()
             }
         }),
     );

crates/application/src/agent/mod.rs

@@ -40,7 +40,8 @@ pub use lifecycle::{
     ListAgentsOutput, LiveStateLeanProvider, McpRuntime, PermissionProjectorRegistry,
     ProviderSessionProvider, ReadAgentContext, ReadAgentContextInput, ReadAgentContextOutput,
     StructuredRoutingMode, StructuredSessionDescriptor, UpdateAgentContext,
-    UpdateAgentContextInput, AGENT_MEMORY_RECALL_BUDGET, LIVE_STATE_INJECT_MAX,
+    UpdateAgentContextInput, DEFAULT_OPENCODE_MCP_TIMEOUT_MS, AGENT_MEMORY_RECALL_BUDGET,
+    LIVE_STATE_INJECT_MAX, resolve_opencode_mcp_timeout_ms,
 };
 pub use resume::{
     ListResumableAgents, ListResumableAgentsInput, ListResumableAgentsOutput, ResumableAgent,