From 93fd34fae437631385d9e08c35e03337e34f1bed Mon Sep 17 00:00:00 2001
From: Vikhyath Mondreti <vikhyath@simstudio.ai>
Date: Sat, 8 Aug 2026 18:31:55 -0700
Subject: [PATCH] fix(condition): stop shipping all block outputs in every
 evaluation
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

ConditionBlockHandler forwarded collectBlockData's full blockData — every
block output accumulated so far in the run — to function_execute on each
condition evaluation. The resolver already inlines every <block.field>
reference into the expression before the handler runs, so that payload was
never read; it only inflated the request body.

Inside a wide subflow one flat blockStates map holds every branch's outputs,
so a 91-branch parallel pushed the body past the 10MB cap and failed the
gate with "Request body size limit exceeded" even though the expression was
just a boolean compare. Per-value large-value offload does not catch this:
its threshold is 8MB for a single value, while this is an aggregate of many
medium ones.

Mirrors FunctionBlockHandler, which moved to blockData: {} in #4560 and left
the condition handler on the old path.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 .../condition/condition-handler.test.ts       | 20 ++++++++++++++++++-
 .../handlers/condition/condition-handler.ts   | 10 ++++++++--
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/apps/sim/executor/handlers/condition/condition-handler.test.ts b/apps/sim/executor/handlers/condition/condition-handler.test.ts
index 6a4af6c4096..fa24cec1bfa 100644
--- a/apps/sim/executor/handlers/condition/condition-handler.test.ts
+++ b/apps/sim/executor/handlers/condition/condition-handler.test.ts
@@ -179,7 +179,7 @@ describe('ConditionBlockHandler', () => {
         timeout: 5000,
         envVars: mockContext.environmentVariables,
         workflowVariables: mockContext.workflowVariables,
-        blockData: { 'source-block-1': { value: 10, text: 'hello' } },
+        blockData: {},
         blockNameMapping: { sourceblock: 'source-block-1' },
         _context: {
           workflowId: 'test-workflow-id',
@@ -190,6 +190,24 @@ describe('ConditionBlockHandler', () => {
     )
   })
 
+  it('should never forward collected block outputs in the request body', async () => {
+    mockCollectBlockData.mockReturnValueOnce({
+      blockData: { 'huge-block': { payload: 'x'.repeat(1024) } },
+      blockNameMapping: { hugeblock: 'huge-block' },
+    })
+    mockExecuteTool.mockResolvedValueOnce({ success: true, output: { result: true } })
+
+    const conditions = [
+      { id: 'cond1', title: 'if', value: 'true' },
+      { id: 'else1', title: 'else', value: '' },
+    ]
+
+    await handler.execute(mockContext, mockBlock, { conditions: JSON.stringify(conditions) })
+
+    const [, toolParams] = mockExecuteTool.mock.calls[0]
+    expect(toolParams.blockData).toEqual({})
+  })
+
   it('should select the else path if other conditions fail', async () => {
     mockExecuteTool.mockResolvedValueOnce({ success: true, output: { result: false } })
 
diff --git a/apps/sim/executor/handlers/condition/condition-handler.ts b/apps/sim/executor/handlers/condition/condition-handler.ts
index ec86ac7640c..d21702ae81f 100644
--- a/apps/sim/executor/handlers/condition/condition-handler.ts
+++ b/apps/sim/executor/handlers/condition/condition-handler.ts
@@ -22,6 +22,12 @@ const CONDITION_TIMEOUT_MS = 5000
  * Evaluates a single condition expression.
  * The resolver preserves legacy Condition expression substitution before this function executes the
  * resulting JavaScript through the shared function execution boundary.
+ *
+ * `blockData` is deliberately empty: the resolver already inlines every `<block.field>` reference
+ * into the expression before this runs, so shipping the run's accumulated block outputs would only
+ * inflate the request body. Sending them blew the 10MB body cap on wide subflows, where a single
+ * flat `blockStates` map holds every branch's outputs.
+ *
  * Returns true if condition is met, false otherwise.
  */
 async function evaluateConditionExpression(
@@ -36,7 +42,7 @@ async function evaluateConditionExpression(
     const contextSetup = `const context = ${JSON.stringify(evalContext)};`
     const code = `${contextSetup}\nreturn Boolean(${conditionExpression})`
 
-    const { blockData, blockNameMapping, blockOutputSchemas } = collectBlockData(ctx, currentNodeId)
+    const { blockNameMapping, blockOutputSchemas } = collectBlockData(ctx, currentNodeId)
 
     const result = await executeTool(
       'function_execute',
@@ -45,7 +51,7 @@ async function evaluateConditionExpression(
         timeout: CONDITION_TIMEOUT_MS,
         envVars: normalizeStringRecord(ctx.environmentVariables),
         workflowVariables: normalizeWorkflowVariables(ctx.workflowVariables),
-        blockData,
+        blockData: {},
         blockNameMapping,
         blockOutputSchemas,
         _context: {