Add server-side workflows with YAML files, task freeze and lead tools

api/openapi.yaml

@@ -236,6 +236,22 @@ paths:
               schema: { $ref: "#/components/schemas/Task" }
         "404": { $ref: "#/components/responses/Error" }
 
+  /api/tasks/{taskId}/workflow:
+    parameters:
+      - { name: taskId, in: path, required: true, schema: { type: string } }
+    get:
+      operationId: getTaskWorkflow
+      description: >
+        The workflow the task froze when it was created, as it was then. Later edits and deletes of the workflow
+        don't change it.
+      responses:
+        "200":
+          description: The frozen workflow.
+          content:
+            application/json:
+              schema: { $ref: "#/components/schemas/TaskWorkflow" }
+        "404": { $ref: "#/components/responses/Error" }
+
   /api/tasks/{taskId}/unmerged:
     parameters:
       - { name: taskId, in: path, required: true, schema: { type: string } }
@@ -781,6 +797,54 @@ paths:
             application/json:
               schema: { $ref: "#/components/schemas/Status" }
 
+  /api/workflows:
+    get:
+      operationId: listWorkflows
+      responses:
+        "200":
+          description: Every workflow's name and description, by name.
+          content:
+            application/json:
+              schema:
+                type: array
+                items: { $ref: "#/components/schemas/WorkflowSummary" }
+
+  /api/workflows/{name}:
+    parameters:
+      - { name: name, in: path, required: true, schema: { type: string } }
+    get:
+      operationId: getWorkflow
+      responses:
+        "200":
+          description: "The workflow's file: its WorkflowDefinition as YAML, as an attachment named after it."
+          content:
+            application/yaml:
+              schema: { type: string }
+        "404": { $ref: "#/components/responses/Error" }
+    put:
+      operationId: putWorkflow
+      description: >
+        Creates or replaces the workflow from its file, a WorkflowDefinition as YAML (or JSON). The name is one line
+        of 1 to 100 characters. Tasks that already froze the workflow keep their copy.
+      requestBody:
+        required: true
+        content:
+          application/yaml:
+            schema: { type: string }
+      responses:
+        "200":
+          description: The stored workflow.
+          content:
+            application/json:
+              schema: { $ref: "#/components/schemas/WorkflowSummary" }
+        "400": { $ref: "#/components/responses/Error" }
+    delete:
+      operationId: deleteWorkflow
+      responses:
+        "204":
+          description: Deleted. Tasks that froze it keep their copy.
+        "404": { $ref: "#/components/responses/Error" }
+
 components:
   responses:
     Error:
@@ -868,6 +932,7 @@ components:
         forked_from: { type: string, description: "The task this one was forked from; absent for other tasks." }
         forked_at: { type: integer, description: "With forked_from: the n of the snapshot it was forked at." }
         merge_queued_at: { type: string, format: date-time, description: "When Merge was requested while another task in the project was merging; absent once the merge starts or when none is held." }
+        workflow: { type: string, description: "The name of the workflow the task froze at creation (getTaskWorkflow has its copy); absent for a task without one." }
 
     Todo:
       type: object
@@ -917,6 +982,48 @@ components:
       required: [title]
       properties:
         title: { type: string }
+        workflow: { type: string, description: "The name of a workflow for the task to freeze: it keeps a copy of the workflow's definition as it is now." }
+
+    WorkflowSummary:
+      type: object
+      required: [name, description]
+      properties:
+        name: { type: string }
+        description: { type: string }
+
+    WorkflowDefinition:
+      type: object
+      description: >
+        A workflow's file, which holds everything but its name: a sequence of stages run in order. Sent and returned
+        as YAML.
+      required: [stages]
+      properties:
+        description: { type: string, x-go-type-skip-optional-pointer: true }
+        stages:
+          type: array
+          minItems: 1
+          items: { $ref: "#/components/schemas/Stage" }
+
+    Stage:
+      type: object
+      required: [name, vendor, model, prompt]
+      properties:
+        name: { type: string, description: "One line of 1 to 100 characters, unique within the workflow." }
+        vendor:
+          type: string
+          enum: [claude, codex]
+          x-enum-varnames: [StageVendorClaude, StageVendorCodex]
+          description: Must be the vendor that runs model (gpt-* models run on Codex, every other model on Claude Code).
+        model: { type: string }
+        prompt: { type: string, description: "The stage agent's instructions." }
+
+    TaskWorkflow:
+      type: object
+      description: The workflow a task froze when it was created, as it was then.
+      required: [name, definition]
+      properties:
+        name: { type: string }
+        definition: { type: string, description: The WorkflowDefinition as YAML. }
 
     TaskChanges:
       type: object