diff --git a/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts b/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
index 75d375af4..37fd2a201 100644
--- a/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
@@ -441,7 +441,7 @@ describe("ClaudeAgentSession redesign invariants", () => {
     }
   });
 
-  test("routes input_json_delta through partial parsing before buffered JSON is complete", async () => {
+  test("waits for complete JSON values before updating tool input from input_json_delta", async () => {
     const session = await createSession();
     const internal = session as unknown as {
       mapPartialEvent: (event: Record<string, unknown>) => AgentTimelineItem[];
@@ -479,7 +479,7 @@ describe("ClaudeAgentSession redesign invariants", () => {
               partial_json: '{"command":"echo ',
             },
           },
-          expectedCommand: "echo ",
+          expectedCommand: "echo seed",
         },
         {
           event: {
@@ -520,7 +520,7 @@ describe("ClaudeAgentSession redesign invariants", () => {
     }
   });
 
-  test("surfaces canonical partial tool input from input_json_delta before JSON is complete", async () => {
+  test("does not surface incomplete string values from input_json_delta", async () => {
     const session = await createSession();
     const internal = session as unknown as {
       mapPartialEvent: (event: Record<string, unknown>) => AgentTimelineItem[];
@@ -551,7 +551,6 @@ describe("ClaudeAgentSession redesign invariants", () => {
 
       expect(internal.toolUseCache.get(toolUseId)?.input).toEqual({
         file_path: "src/message.tsx",
-        old_string: "before",
       });
     } finally {
       await session.close();
diff --git a/packages/server/src/server/agent/providers/claude/partial-json.test.ts b/packages/server/src/server/agent/providers/claude/partial-json.test.ts
index f4dafb13e..3d9694a4d 100644
--- a/packages/server/src/server/agent/providers/claude/partial-json.test.ts
+++ b/packages/server/src/server/agent/providers/claude/partial-json.test.ts
@@ -13,33 +13,25 @@ describe("parsePartialJsonObject", () => {
     });
   });
 
-  it("keeps partial string values without field-specific logic", () => {
+  it("does not emit incomplete string values", () => {
     expect(parsePartialJsonObject('{"command":"echo ')).toEqual({
-      value: {
-        command: "echo ",
-      },
+      value: {},
       complete: false,
     });
   });
 
-  it("returns parsed prefix fields from incomplete objects", () => {
+  it("returns only complete prefix fields from incomplete objects", () => {
     expect(parsePartialJsonObject('{"file_path":"src/message.tsx","old_string":"before')).toEqual({
       value: {
         file_path: "src/message.tsx",
-        old_string: "before",
       },
       complete: false,
     });
   });
 
-  it("parses nested partial values generically", () => {
+  it("does not emit incomplete nested values", () => {
     expect(parsePartialJsonObject('{"payload":{"path":"src/index.ts","content":"hello')).toEqual({
-      value: {
-        payload: {
-          path: "src/index.ts",
-          content: "hello",
-        },
-      },
+      value: {},
       complete: false,
     });
   });
diff --git a/packages/server/src/server/agent/providers/claude/partial-json.ts b/packages/server/src/server/agent/providers/claude/partial-json.ts
index ca6611a4e..8e8ef3451 100644
--- a/packages/server/src/server/agent/providers/claude/partial-json.ts
+++ b/packages/server/src/server/agent/providers/claude/partial-json.ts
@@ -271,17 +271,17 @@ function parsePartialObject(
       };
     }
 
-    value[parsedKey.value] = parsedMemberValue.value;
-    currentIndex = skipWhitespace(input, parsedMemberValue.nextIndex);
-
     if (!parsedMemberValue.complete) {
       return {
         value,
-        nextIndex: currentIndex,
+        nextIndex: skipWhitespace(input, parsedMemberValue.nextIndex),
         complete: false,
       };
     }
 
+    value[parsedKey.value] = parsedMemberValue.value;
+    currentIndex = skipWhitespace(input, parsedMemberValue.nextIndex);
+
     const delimiter = input[currentIndex];
     if (delimiter === ",") {
       currentIndex += 1;