🤖 refactor: remove duplicate partial deletion from IPC handler

interruptStream() now owns the complete interrupt flow including partial
deletion. The IPC handler is now a thin wrapper that delegates fully.

This eliminates duplication - previously both layers were deleting the partial
when abandonPartial=true, making two calls to deletePartial() for IPC-triggered
interrupts (though the second was idempotent).

Single source of truth: AgentSession.interruptStream() handles everything.

Author: ethanndickson

src/node/services/agentSession.ts

@@ -377,7 +377,6 @@ export class AgentSession {
     }
 
     // Delete partial when abandoning to prevent commitToHistory from reintroducing it
-    // Mirrors the IPC handler pattern (ipcMain.ts:1108-1110)
     if (abandonPartial) {
       const deleteResult = await this.partialService.deletePartial(this.workspaceId);
       if (!deleteResult.success) {

src/node/services/ipcMain.ts

@@ -1104,12 +1104,6 @@ export class IpcMain {
             return { success: false, error: stopResult.error };
           }
 
-          // If abandonPartial is true, delete the partial instead of committing it
-          if (options?.abandonPartial) {
-            log.debug("Abandoning partial for workspace:", workspaceId);
-            await this.partialService.deletePartial(workspaceId);
-          }
-
           return { success: true, data: undefined };
         } catch (error) {
           const errorMessage = error instanceof Error ? error.message : String(error);