feat: cache provider slash commands on project creation and session start

apps/server/integration/TestProviderAdapter.integration.ts

@@ -488,6 +488,7 @@ export const makeTestProviderAdapterHarness = (options?: MakeTestProviderAdapter
       readThread,
       rollbackThread,
       stopAll,
+      discoverSlashCommands: () => Effect.succeed([]),
       streamEvents: Stream.fromQueue(runtimeEvents),
     };
 

apps/server/src/checkpointing/Layers/CheckpointDiffQuery.test.ts

@@ -33,6 +33,7 @@ function makeSnapshot(input: {
         workspaceRoot: input.workspaceRoot,
         defaultModelSelection: null,
         scripts: [],
+        cachedProviderSlashCommands: {},
         createdAt: "2026-01-01T00:00:00.000Z",
         updatedAt: "2026-01-01T00:00:00.000Z",
         deletedAt: null,

apps/server/src/orchestration/Layers/CheckpointReactor.test.ts

@@ -93,6 +93,7 @@ function createProviderServiceHarness(
     listSessions,
     getCapabilities: () => Effect.succeed({ sessionModelSwitch: "in-session" }),
     rollbackConversation,
+    discoverSlashCommands: () => Effect.succeed([]),
     streamEvents: Stream.fromPubSub(runtimeEventPubSub),
   };
 
@@ -355,6 +356,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -431,6 +433,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: asTurnId("turn-main"),
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -508,6 +511,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -566,6 +570,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -654,6 +659,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: asTurnId("turn-missing-cwd"),
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -701,6 +707,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -751,6 +758,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -803,6 +811,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -881,6 +890,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,
@@ -950,6 +960,7 @@ describe("CheckpointReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: createdAt,
         },
         createdAt,

apps/server/src/orchestration/Layers/OrchestrationEngine.ts

@@ -37,6 +37,7 @@ function commandToAggregateRef(command: OrchestrationCommand): {
     case "project.create":
     case "project.meta.update":
     case "project.delete":
+    case "project.provider-slash-commands.set":
       return {
         aggregateKind: "project",
         aggregateId: command.projectId,

apps/server/src/orchestration/Layers/ProjectionPipeline.test.ts

@@ -1784,6 +1784,7 @@ it.effect("restores pending turn-start metadata across projection pipeline resta
             runtimeMode: "approval-required",
             activeTurnId: turnId,
             lastError: null,
+            providerSlashCommands: [],
             updatedAt: sessionSetAt,
           },
         },

apps/server/src/orchestration/Layers/ProjectionPipeline.ts

@@ -385,6 +385,7 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
             workspaceRoot: event.payload.workspaceRoot,
             defaultModelSelection: event.payload.defaultModelSelection,
             scripts: event.payload.scripts,
+            cachedProviderSlashCommandsJson: null,
             createdAt: event.payload.createdAt,
             updatedAt: event.payload.updatedAt,
             deletedAt: null,
@@ -428,6 +429,26 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
           return;
         }
 
+        case "project.provider-slash-commands-set": {
+          const existingRow = yield* projectionProjectRepository.getById({
+            projectId: event.payload.projectId,
+          });
+          if (Option.isNone(existingRow)) {
+            return;
+          }
+          // Merge new provider commands into existing cached map.
+          const existingCache: Record<string, unknown> = existingRow.value.cachedProviderSlashCommandsJson
+            ? JSON.parse(existingRow.value.cachedProviderSlashCommandsJson)
+            : {};
+          existingCache[event.payload.provider] = event.payload.commands;
+          yield* projectionProjectRepository.upsert({
+            ...existingRow.value,
+            cachedProviderSlashCommandsJson: JSON.stringify(existingCache),
+            updatedAt: event.payload.updatedAt,
+          });
+          return;
+        }
+
         default:
           return;
       }
@@ -803,13 +824,18 @@ const makeOrchestrationProjectionPipeline = Effect.fn("makeOrchestrationProjecti
       if (event.type !== "thread.session-set") {
         return;
       }
+      const providerSlashCommands = event.payload.session.providerSlashCommands;
       yield* projectionThreadSessionRepository.upsert({
         threadId: event.payload.threadId,
         status: event.payload.session.status,
         providerName: event.payload.session.providerName,
         runtimeMode: event.payload.session.runtimeMode,
         activeTurnId: event.payload.session.activeTurnId,
         lastError: event.payload.session.lastError,
+        providerSlashCommandsJson:
+          providerSlashCommands && providerSlashCommands.length > 0
+            ? JSON.stringify(providerSlashCommands)
+            : null,
         updatedAt: event.payload.session.updatedAt,
       });
     });

apps/server/src/orchestration/Layers/ProjectionSnapshotQuery.test.ts

@@ -247,6 +247,7 @@ projectionSnapshotLayer("ProjectionSnapshotQuery", (it) => {
               runOnWorktreeCreate: false,
             },
           ],
+          cachedProviderSlashCommands: {},
           createdAt: "2026-02-24T00:00:00.000Z",
           updatedAt: "2026-02-24T00:00:01.000Z",
           deletedAt: null,
@@ -332,6 +333,7 @@ projectionSnapshotLayer("ProjectionSnapshotQuery", (it) => {
             runtimeMode: "approval-required",
             activeTurnId: asTurnId("turn-1"),
             lastError: null,
+            providerSlashCommands: [],
             updatedAt: "2026-02-24T00:00:07.000Z",
           },
         },

apps/server/src/orchestration/Layers/ProjectionSnapshotQuery.ts

@@ -68,7 +68,11 @@ const ProjectionThreadActivityDbRowSchema = ProjectionThreadActivity.mapFields(
     sequence: Schema.NullOr(NonNegativeInt),
   }),
 );
-const ProjectionThreadSessionDbRowSchema = ProjectionThreadSession;
+const ProjectionThreadSessionDbRowSchema = ProjectionThreadSession.mapFields(
+  Struct.assign({
+    providerSlashCommandsJson: Schema.NullOr(Schema.String),
+  }),
+);
 const ProjectionCheckpointDbRowSchema = ProjectionCheckpoint.mapFields(
   Struct.assign({
     files: Schema.fromJsonString(Schema.Array(OrchestrationCheckpointFile)),
@@ -149,6 +153,7 @@ const makeProjectionSnapshotQuery = Effect.gen(function* () {
           workspace_root AS "workspaceRoot",
           default_model_selection_json AS "defaultModelSelection",
           scripts_json AS "scripts",
+          cached_provider_slash_commands_json AS "cachedProviderSlashCommandsJson",
           created_at AS "createdAt",
           updated_at AS "updatedAt",
           deleted_at AS "deletedAt"
@@ -259,6 +264,7 @@ const makeProjectionSnapshotQuery = Effect.gen(function* () {
           runtime_mode AS "runtimeMode",
           active_turn_id AS "activeTurnId",
           last_error AS "lastError",
+          provider_slash_commands_json AS "providerSlashCommandsJson",
           updated_at AS "updatedAt"
         FROM projection_thread_sessions
         ORDER BY thread_id ASC
@@ -527,27 +533,50 @@ const makeProjectionSnapshotQuery = Effect.gen(function* () {
 
           for (const row of sessionRows) {
             updatedAt = maxIso(updatedAt, row.updatedAt);
+            const providerSlashCommands: Array<string> = (() => {
+              const json = row.providerSlashCommandsJson;
+              if (!json) return [];
+              try {
+                const parsed: unknown = JSON.parse(json);
+                return Array.isArray(parsed) ? (parsed as Array<string>) : [];
+              } catch {
+                return [];
+              }
+            })();
             sessionsByThread.set(row.threadId, {
               threadId: row.threadId,
               status: row.status,
               providerName: row.providerName,
               runtimeMode: row.runtimeMode,
               activeTurnId: row.activeTurnId,
               lastError: row.lastError,
+              providerSlashCommands,
               updatedAt: row.updatedAt,
             });
           }
 
-          const projects: ReadonlyArray<OrchestrationProject> = projectRows.map((row) => ({
-            id: row.projectId,
-            title: row.title,
-            workspaceRoot: row.workspaceRoot,
-            defaultModelSelection: row.defaultModelSelection,
-            scripts: row.scripts,
-            createdAt: row.createdAt,
-            updatedAt: row.updatedAt,
-            deletedAt: row.deletedAt,
-          }));
+          const projects: ReadonlyArray<OrchestrationProject> = projectRows.map((row) => {
+            const cachedProviderSlashCommands: OrchestrationProject["cachedProviderSlashCommands"] =
+              (() => {
+                if (!row.cachedProviderSlashCommandsJson) return {};
+                try {
+                  return JSON.parse(row.cachedProviderSlashCommandsJson) as OrchestrationProject["cachedProviderSlashCommands"];
+                } catch {
+                  return {};
+                }
+              })();
+            return {
+              id: row.projectId,
+              title: row.title,
+              workspaceRoot: row.workspaceRoot,
+              defaultModelSelection: row.defaultModelSelection,
+              scripts: row.scripts,
+              cachedProviderSlashCommands,
+              createdAt: row.createdAt,
+              updatedAt: row.updatedAt,
+              deletedAt: row.deletedAt,
+            };
+          });
 
           const threads: ReadonlyArray<OrchestrationThread> = threadRows.map((row) => ({
             id: row.threadId,

apps/server/src/orchestration/Layers/ProviderCommandReactor.test.ts

@@ -207,6 +207,7 @@ describe("ProviderCommandReactor", () => {
           sessionModelSwitch: input?.sessionModelSwitch ?? "in-session",
         }),
       rollbackConversation: () => unsupported(),
+      discoverSlashCommands: () => Effect.succeed([]),
       streamEvents: Stream.fromPubSub(runtimeEventPubSub),
     };
 
@@ -1038,6 +1039,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "full-access",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1222,6 +1224,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: asTurnId("turn-1"),
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1260,6 +1263,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1301,6 +1305,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1355,6 +1360,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1452,6 +1458,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,
@@ -1554,6 +1561,7 @@ describe("ProviderCommandReactor", () => {
           runtimeMode: "approval-required",
           activeTurnId: null,
           lastError: null,
+          providerSlashCommands: [],
           updatedAt: now,
         },
         createdAt: now,