feat(core): edit-based workflow generation and stronger validator typing

.changeset/accumulator-output-types.md

@@ -0,0 +1,5 @@
+---
+"@remoraflow/core": patch
+---
+
+The validator now types a `for-each` or `while` accumulator from its loop body's output, so an accumulator that builds the wrong shape is reported as an error. It warns separately when the initial value, which the loop outputs if the body never runs, does not match the body's output. Type inference also flattens lists of arrays correctly, types empty literal arrays as arrays with no items, checks each member of a union and each tuple item against the target schema, and treats different JSON Schema types as disjoint. The `for-each` and `while` step descriptions now explain how to collect outputs without an accumulator and how to append to an array accumulator.

.changeset/faster-workflow-definition-schema.md

@@ -0,0 +1,5 @@
+---
+"@remoraflow/core": patch
+---
+
+The workflow definition schema is about twice as fast to build, because the union of step types is now built in one call instead of a chain of `.or()` and `.exclude()` calls.

.changeset/switch-case-forwards-branch-output.md

@@ -0,0 +1,5 @@
+---
+"@remoraflow/core": minor
+---
+
+A `switch-case` step's output is now the value returned by its selected branch, instead of `null`. The validator types it as the union of the branch outputs. Field access on a union type no longer warns when every member of the union has the field.

.changeset/validate-jmespath-function-names.md

@@ -0,0 +1,6 @@
+---
+"@remoraflow/core": patch
+"@remoraflow/ui": patch
+---
+
+The validator now reports calls to JMESPath functions that do not exist, such as `append()`, instead of letting them fail at runtime. The list of JMESPath functions is exported as `JMESPATH_FUNCTION_NAMES`, and the UI's syntax highlighting uses it.

.changeset/workflow-editor-tools.md

@@ -0,0 +1,5 @@
+---
+"@remoraflow/core": minor
+---
+
+Workflow generation now edits a draft workflow in place instead of resubmitting the full definition on every attempt. The agent uses `write-workflow`, `read-workflow` (JMESPath), `edit-workflow` (JSON Patch), and `submit-workflow`. Write and edit return validation diagnostics without failing the tool call, edits also return the changed workflow, and both accept `submitIfValid` to submit a workflow that has no errors or warnings without a separate call. An edit that uses `replace` on a field that does not exist adds the field. When a required output schema is given and the workflow declares no `outputSchema`, the required schema is used. Tool calls whose top-level object or array arguments were sent as JSON strings are repaired. The generation instructions are marked as an Anthropic prompt-cache breakpoint. `step-end` diagnostic events now include each step's tool calls, with the input and error of failed calls.

packages/core/package.json

@@ -44,6 +44,7 @@
         "arktype": "^2.1.29",
         "capture-console": "^1.0.2",
         "dedent": "^1.7.2",
+        "fast-json-patch": "^3.1.1",
         "jmespath": "^0.16.0",
         "tokenx": "^1.3.0",
         "zod": "^4.4.3"
@@ -61,8 +62,10 @@
         }
     },
     "devDependencies": {
-        "@ai-sdk/openai": "^4.0.43",
+        "@ai-sdk/amazon-bedrock": "5.0.58",
+        "@ai-sdk/openai-compatible": "3.0.31",
         "@ai-sdk/provider-utils": "5.0.27",
+        "@aws-sdk/credential-providers": "^3.1139.0",
         "@aws/durable-execution-sdk-js": "^1.1.0",
         "@aws/durable-execution-sdk-js-testing": "^1.1.1",
         "@temporalio/client": "^1.23.0",

packages/core/src/execution/step-executors/index.test.ts

@@ -218,6 +218,15 @@ describe("step executors", () => {
             expect(result.scope?.fallback).toBe("D");
         });
 
+        test("outputs the selected branch's return value", async () => {
+            const result = await runStep(
+                switchStep,
+                { x: "a" },
+                { workflowDefinition: workflow(switchStep, matched, fallback) },
+            );
+            expect(result.scope?.sc).toBe("A");
+        });
+
         test("errors with UNRECOGNIZED_CASE when nothing matches", async () => {
             const noDefault = step("sc", {
                 type: "switch-case",

packages/core/src/execution/step-executors/switch-case.ts

@@ -74,7 +74,11 @@ export const switchCaseExecutor: StepExecutor<"switch-case"> = {
         }
         const branchScope = lastUpdate?.scope ?? scope;
         yield {
-            scope: { ...scope, ...branchScope },
+            scope: {
+                ...scope,
+                ...branchScope,
+                [step.id]: lastUpdate?.output ?? null,
+            },
             output: null,
             error: null,
             ...(step.nextStepId

packages/core/src/execution/step-output-contract.test.ts

@@ -208,11 +208,13 @@ const CONTRACT_CASES: Record<WorkflowStep["type"], ContractCase> = {
                     ],
                 },
             }),
-            step("body", { type: "start" }),
+            step("body", {
+                type: "end",
+                params: { output: { type: "literal", value: "picked" } },
+            }),
         ],
-        // `switch-case` merges the branch scope but binds nothing under its own id.
-        expectedOutput: undefined,
-        conformance: "verified",
+        expectedOutput: "picked",
+        conformance: "unconstrained",
     },
     "wait-for-condition": {
         steps: [