diff --git a/internal/js/helpers/stream-tool-sieve/parse.js b/internal/js/helpers/stream-tool-sieve/parse.js
index 92fabc3..bf21046 100644
--- a/internal/js/helpers/stream-tool-sieve/parse.js
+++ b/internal/js/helpers/stream-tool-sieve/parse.js
@@ -1,14 +1,14 @@
 'use strict';
 
-const TOOL_CALL_PATTERN = /\{\s*["']tool_calls["']\s*:\s*\[(.*?)\]\s*\}/s;
-
 const {
   toStringSafe,
   looksLikeToolExampleContext,
 } = require('./state');
 const {
-  extractJSONObjectFrom,
-} = require('./jsonscan');
+  stripFencedCodeBlocks,
+  buildToolCallCandidates,
+  parseToolCallsPayload,
+} = require('./parse_payload');
 
 function extractToolNames(tools) {
   if (!Array.isArray(tools) || tools.length === 0) {
@@ -63,14 +63,6 @@ function parseToolCallsDetailed(text, toolNames) {
   return result;
 }
 
-function stripFencedCodeBlocks(text) {
-  const t = typeof text === 'string' ? text : '';
-  if (!t) {
-    return '';
-  }
-  return t.replace(/```[\s\S]*?```/g, ' ');
-}
-
 function parseStandaloneToolCalls(text, toolNames) {
   return parseStandaloneToolCallsDetailed(text, toolNames).calls;
 }
@@ -111,169 +103,11 @@ function emptyParseResult() {
   };
 }
 
-function buildToolCallCandidates(text) {
-  const trimmed = toStringSafe(text);
-  const candidates = [trimmed];
-  const fenced = trimmed.match(/```(?:json)?\s*([\s\S]*?)\s*```/gi) || [];
-  for (const block of fenced) {
-    const m = block.match(/```(?:json)?\s*([\s\S]*?)\s*```/i);
-    if (m && m[1]) {
-      candidates.push(toStringSafe(m[1]));
-    }
-  }
-  for (const candidate of extractToolCallObjects(trimmed)) {
-    candidates.push(toStringSafe(candidate));
-  }
-  const first = trimmed.indexOf('{');
-  const last = trimmed.lastIndexOf('}');
-  if (first >= 0 && last > first) {
-    candidates.push(toStringSafe(trimmed.slice(first, last + 1)));
-  }
-  const m = trimmed.match(TOOL_CALL_PATTERN);
-  if (m && m[1]) {
-    candidates.push(`{"tool_calls":[${m[1]}]}`);
-  }
-  return [...new Set(candidates.filter(Boolean))];
-}
-
-function extractToolCallObjects(text) {
-  const raw = toStringSafe(text);
-  if (!raw) {
-    return [];
-  }
-  const lower = raw.toLowerCase();
-  const out = [];
-  let offset = 0;
-  // eslint-disable-next-line no-constant-condition
-  while (true) {
-    let idx = lower.indexOf('tool_calls', offset);
-    if (idx < 0) {
-      break;
-    }
-    let start = raw.slice(0, idx).lastIndexOf('{');
-    while (start >= 0) {
-      const obj = extractJSONObjectFrom(raw, start);
-      if (obj.ok) {
-        out.push(raw.slice(start, obj.end).trim());
-        offset = obj.end;
-        idx = -1;
-        break;
-      }
-      start = raw.slice(0, start).lastIndexOf('{');
-    }
-    if (idx >= 0) {
-      offset = idx + 'tool_calls'.length;
-    }
-  }
-  return out;
-}
-
-function parseToolCallsPayload(payload) {
-  let decoded;
-  try {
-    decoded = JSON.parse(payload);
-  } catch (_err) {
-    return [];
-  }
-  if (Array.isArray(decoded)) {
-    return parseToolCallList(decoded);
-  }
-  if (!decoded || typeof decoded !== 'object') {
-    return [];
-  }
-  if (decoded.tool_calls) {
-    return parseToolCallList(decoded.tool_calls);
-  }
-  const one = parseToolCallItem(decoded);
-  return one ? [one] : [];
-}
-
-function parseToolCallList(v) {
-  if (!Array.isArray(v)) {
-    return [];
-  }
-  const out = [];
-  for (const item of v) {
-    if (!item || typeof item !== 'object') {
-      continue;
-    }
-    const one = parseToolCallItem(item);
-    if (one) {
-      out.push(one);
-    }
-  }
-  return out;
-}
-
-function parseToolCallItem(m) {
-  let name = toStringSafe(m.name);
-  let inputRaw = m.input;
-  let hasInput = Object.prototype.hasOwnProperty.call(m, 'input');
-  const fn = m.function && typeof m.function === 'object' ? m.function : null;
-  if (fn) {
-    if (!name) {
-      name = toStringSafe(fn.name);
-    }
-    if (!hasInput && Object.prototype.hasOwnProperty.call(fn, 'arguments')) {
-      inputRaw = fn.arguments;
-      hasInput = true;
-    }
-  }
-  if (!hasInput) {
-    for (const k of ['arguments', 'args', 'parameters', 'params']) {
-      if (Object.prototype.hasOwnProperty.call(m, k)) {
-        inputRaw = m[k];
-        hasInput = true;
-        break;
-      }
-    }
-  }
-  if (!name) {
-    return null;
-  }
-  return {
-    name,
-    input: parseToolCallInput(inputRaw),
-  };
-}
-
-function parseToolCallInput(v) {
-  if (v == null) {
-    return {};
-  }
-  if (typeof v === 'string') {
-    const raw = toStringSafe(v);
-    if (!raw) {
-      return {};
-    }
-    try {
-      const parsed = JSON.parse(raw);
-      if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
-        return parsed;
-      }
-      return { _raw: raw };
-    } catch (_err) {
-      return { _raw: raw };
-    }
-  }
-  if (typeof v === 'object' && !Array.isArray(v)) {
-    return v;
-  }
-  try {
-    const parsed = JSON.parse(JSON.stringify(v));
-    if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
-      return parsed;
-    }
-  } catch (_err) {
-    return {};
-  }
-  return {};
-}
-
 function filterToolCallsDetailed(parsed, toolNames) {
+  const sourceNames = Array.isArray(toolNames) ? toolNames : [];
   const allowed = new Set();
   const allowedCanonical = new Map();
-  for (const item of toolNames || []) {
+  for (const item of sourceNames) {
     const name = toStringSafe(item);
     if (!name) {
       continue;
diff --git a/internal/js/helpers/stream-tool-sieve/parse_payload.js b/internal/js/helpers/stream-tool-sieve/parse_payload.js
new file mode 100644
index 0000000..4be82c4
--- /dev/null
+++ b/internal/js/helpers/stream-tool-sieve/parse_payload.js
@@ -0,0 +1,196 @@
+'use strict';
+
+const TOOL_CALL_PATTERN = /\{\s*["']tool_calls["']\s*:\s*\[(.*?)\]\s*\}/s;
+
+const {
+  toStringSafe,
+} = require('./state');
+const {
+  extractJSONObjectFrom,
+} = require('./jsonscan');
+
+function stripFencedCodeBlocks(text) {
+  const t = typeof text === 'string' ? text : '';
+  if (!t) {
+    return '';
+  }
+  return t.replace(/```[\s\S]*?```/g, ' ');
+}
+
+function buildToolCallCandidates(text) {
+  const trimmed = toStringSafe(text);
+  const candidates = [trimmed];
+
+  const fenced = trimmed.match(/```(?:json)?\s*([\s\S]*?)\s*```/gi) || [];
+  for (const block of fenced) {
+    const m = block.match(/```(?:json)?\s*([\s\S]*?)\s*```/i);
+    if (m && m[1]) {
+      candidates.push(toStringSafe(m[1]));
+    }
+  }
+
+  for (const candidate of extractToolCallObjects(trimmed)) {
+    candidates.push(toStringSafe(candidate));
+  }
+
+  const first = trimmed.indexOf('{');
+  const last = trimmed.lastIndexOf('}');
+  if (first >= 0 && last > first) {
+    candidates.push(toStringSafe(trimmed.slice(first, last + 1)));
+  }
+
+  const m = trimmed.match(TOOL_CALL_PATTERN);
+  if (m && m[1]) {
+    candidates.push(`{"tool_calls":[${m[1]}]}`);
+  }
+
+  return [...new Set(candidates.filter(Boolean))];
+}
+
+function extractToolCallObjects(text) {
+  const raw = toStringSafe(text);
+  if (!raw) {
+    return [];
+  }
+  const lower = raw.toLowerCase();
+  const out = [];
+  let offset = 0;
+
+  // eslint-disable-next-line no-constant-condition
+  while (true) {
+    let idx = lower.indexOf('tool_calls', offset);
+    if (idx < 0) {
+      break;
+    }
+    let start = raw.slice(0, idx).lastIndexOf('{');
+    while (start >= 0) {
+      const obj = extractJSONObjectFrom(raw, start);
+      if (obj.ok) {
+        out.push(raw.slice(start, obj.end).trim());
+        offset = obj.end;
+        idx = -1;
+        break;
+      }
+      start = raw.slice(0, start).lastIndexOf('{');
+    }
+    if (idx >= 0) {
+      offset = idx + 'tool_calls'.length;
+    }
+  }
+
+  return out;
+}
+
+function parseToolCallsPayload(payload) {
+  let decoded;
+  try {
+    decoded = JSON.parse(payload);
+  } catch (_err) {
+    return [];
+  }
+
+  if (Array.isArray(decoded)) {
+    return parseToolCallList(decoded);
+  }
+  if (!decoded || typeof decoded !== 'object') {
+    return [];
+  }
+  if (decoded.tool_calls) {
+    return parseToolCallList(decoded.tool_calls);
+  }
+
+  const one = parseToolCallItem(decoded);
+  return one ? [one] : [];
+}
+
+function parseToolCallList(v) {
+  if (!Array.isArray(v)) {
+    return [];
+  }
+  const out = [];
+  for (const item of v) {
+    if (!item || typeof item !== 'object') {
+      continue;
+    }
+    const one = parseToolCallItem(item);
+    if (one) {
+      out.push(one);
+    }
+  }
+  return out;
+}
+
+function parseToolCallItem(m) {
+  let name = toStringSafe(m.name);
+  let inputRaw = m.input;
+  let hasInput = Object.prototype.hasOwnProperty.call(m, 'input');
+  const fn = m.function && typeof m.function === 'object' ? m.function : null;
+
+  if (fn) {
+    if (!name) {
+      name = toStringSafe(fn.name);
+    }
+    if (!hasInput && Object.prototype.hasOwnProperty.call(fn, 'arguments')) {
+      inputRaw = fn.arguments;
+      hasInput = true;
+    }
+  }
+
+  if (!hasInput) {
+    for (const k of ['arguments', 'args', 'parameters', 'params']) {
+      if (Object.prototype.hasOwnProperty.call(m, k)) {
+        inputRaw = m[k];
+        hasInput = true;
+        break;
+      }
+    }
+  }
+
+  if (!name) {
+    return null;
+  }
+
+  return {
+    name,
+    input: parseToolCallInput(inputRaw),
+  };
+}
+
+function parseToolCallInput(v) {
+  if (v == null) {
+    return {};
+  }
+  if (typeof v === 'string') {
+    const raw = toStringSafe(v);
+    if (!raw) {
+      return {};
+    }
+    try {
+      const parsed = JSON.parse(raw);
+      if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
+        return parsed;
+      }
+      return { _raw: raw };
+    } catch (_err) {
+      return { _raw: raw };
+    }
+  }
+  if (typeof v === 'object' && !Array.isArray(v)) {
+    return v;
+  }
+  try {
+    const parsed = JSON.parse(JSON.stringify(v));
+    if (parsed && typeof parsed === 'object' && !Array.isArray(parsed)) {
+      return parsed;
+    }
+  } catch (_err) {
+    return {};
+  }
+  return {};
+}
+
+module.exports = {
+  stripFencedCodeBlocks,
+  buildToolCallCandidates,
+  parseToolCallsPayload,
+};
diff --git a/plans/refactor-line-gate-targets.txt b/plans/refactor-line-gate-targets.txt
index c9839b2..645b7e1 100644
--- a/plans/refactor-line-gate-targets.txt
+++ b/plans/refactor-line-gate-targets.txt
@@ -105,7 +105,6 @@ internal/js/helpers/stream-tool-sieve.js
 internal/js/helpers/stream-tool-sieve/index.js
 internal/js/helpers/stream-tool-sieve/state.js
 internal/js/helpers/stream-tool-sieve/sieve.js
-internal/js/helpers/stream-tool-sieve/incremental.js
 internal/js/helpers/stream-tool-sieve/jsonscan.js
 internal/js/helpers/stream-tool-sieve/parse.js
 internal/js/helpers/stream-tool-sieve/format.js