fix(agent-v2): make workflow context value truncation length configurable

The Agent v2 node hard-coded a 2000-character cutoff for previous node
output values embedded in the workflow context prompt, silently
dropping content beyond that length. Move the limit to
WORKFLOW_AGENT_V2_CONTEXT_VALUE_MAX_LENGTH (default 400000, matching
TEMPLATE_TRANSFORM_MAX_LENGTH) so long outputs are no longer truncated
by default and the limit can be tuned when needed.

Fixes #40729

api/configs/feature/__init__.py

@@ -897,6 +897,14 @@ class WorkflowConfig(BaseSettings):
         default=5,
     )
 
+    WORKFLOW_AGENT_V2_CONTEXT_VALUE_MAX_LENGTH: PositiveInt = Field(
+        description=(
+            "Maximum number of characters for a previous node output value included "
+            "in an Agent node's workflow context before it is truncated"
+        ),
+        default=400_000,
+    )
+
     MAX_VARIABLE_SIZE: PositiveInt = Field(
         description="Maximum size in bytes for a single variable in workflows. Default to 200 KB.",
         default=200 * 1024,

api/core/workflow/nodes/agent_v2/runtime_request_builder.py

@@ -436,8 +436,9 @@ class WorkflowAgentRuntimeRequestBuilder:
             return json.dumps(prompt_payload, ensure_ascii=False, separators=(",", ":"))
 
         text = str(value)
-        if len(text) > 2000:
-            return text[:2000] + "...[truncated]"
+        max_length = dify_config.WORKFLOW_AGENT_V2_CONTEXT_VALUE_MAX_LENGTH
+        if len(text) > max_length:
+            return text[:max_length] + "...[truncated]"
         return text
 
     @classmethod

api/tests/unit_tests/core/workflow/nodes/agent_v2/test_runtime_request_builder.py

@@ -1398,6 +1398,47 @@ def test_previous_node_remote_url_file_mapping_is_not_truncated_in_workflow_cont
     assert "...[truncated]" not in _workflow_user_prompt(result)
 
 
+def test_previous_node_long_text_output_is_not_truncated_under_default_limit():
+    long_text = "a" * 2500
+
+    class LongTextVariablePool(FakeVariablePool):
+        def get(self, selector):
+            if list(selector) == ["previous-node", "text"]:
+                return StringSegment(value=long_text)
+            return super().get(selector)
+
+    context = replace(_context(), variable_pool=LongTextVariablePool())
+    context.binding.node_job_config = WorkflowNodeJobConfig.model_validate(
+        {
+            "workflow_prompt": "Review {{#previous-node.text#}} before responding.",
+        }
+    )
+
+    result = WorkflowAgentRuntimeRequestBuilder(credentials_provider=FakeCredentialsProvider()).build(context)
+
+    user_prompt = _workflow_user_prompt(result)
+    assert f"  - previous-node.text: {long_text}" in user_prompt
+    assert "...[truncated]" not in user_prompt
+
+
+def test_previous_node_text_output_respects_configured_max_length(monkeypatch):
+    monkeypatch.setattr(
+        "core.workflow.nodes.agent_v2.runtime_request_builder.dify_config.WORKFLOW_AGENT_V2_CONTEXT_VALUE_MAX_LENGTH",
+        10,
+    )
+    context = _context()
+    context.binding.node_job_config = WorkflowNodeJobConfig.model_validate(
+        {
+            "workflow_prompt": "Review {{#previous-node.text#}} before responding.",
+        }
+    )
+
+    result = WorkflowAgentRuntimeRequestBuilder(credentials_provider=FakeCredentialsProvider()).build(context)
+
+    user_prompt = _workflow_user_prompt(result)
+    assert "  - previous-node.text: Previous r...[truncated]" in user_prompt
+
+
 # ── Agent config declaration layer ────────────────────────────────────────────
 
 

docker/envs/core-services/shared.env.example

@@ -201,6 +201,7 @@ TEMPLATE_TRANSFORM_MAX_LENGTH=400000
 WORKFLOW_MAX_EXECUTION_STEPS=500
 WORKFLOW_MAX_EXECUTION_TIME=1200
 WORKFLOW_CALL_MAX_DEPTH=5
+WORKFLOW_AGENT_V2_CONTEXT_VALUE_MAX_LENGTH=400000
 MAX_VARIABLE_SIZE=204800
 WORKFLOW_GENERATOR_NODE_BUILDER_MAX_WORKERS=6
 WORKFLOW_FILE_UPLOAD_LIMIT=10