diff --git a/cli/main.py b/cli/main.py
index d9a9d023..3ed61212 100644
--- a/cli/main.py
+++ b/cli/main.py
@@ -1,6 +1,7 @@
 from typing import Optional
 import datetime
 import json
+from tradingagents.agents.utils.json_utils import extract_json
 import typer
 from pathlib import Path
 from functools import wraps
@@ -1216,7 +1217,7 @@ def run_scan(date: Optional[str] = None):
 
         # Try to parse and show watchlist table
         try:
-            summary_data = json.loads(summary)
+            summary_data = extract_json(summary)
             stocks = summary_data.get("stocks_to_investigate", [])
             if stocks:
                 table = Table(title="Stocks to Investigate", box=box.ROUNDED)
@@ -1234,7 +1235,7 @@ def run_scan(date: Optional[str] = None):
                         s.get("thesis_angle", ""),
                     )
                 console.print(table)
-        except (json.JSONDecodeError, KeyError):
+        except (json.JSONDecodeError, KeyError, ValueError):
             pass  # Summary wasn't valid JSON — already printed as markdown
 
 
diff --git a/docs/agent/decisions/002-data-vendor-fallback.md b/docs/agent/decisions/002-data-vendor-fallback.md
index c8d9434b..6af51f00 100644
--- a/docs/agent/decisions/002-data-vendor-fallback.md
+++ b/docs/agent/decisions/002-data-vendor-fallback.md
@@ -1,6 +1,7 @@
 ---
 type: decision
-status: active
+status: superseded
+superseded_by: 011-opt-in-vendor-fallback
 date: 2026-03-17
 agent_author: "claude"
 tags: [data, alpha-vantage, yfinance, fallback]
diff --git a/docs/agent/decisions/008-lessons-learned.md b/docs/agent/decisions/008-lessons-learned.md
index ac423402..a7f89e08 100644
--- a/docs/agent/decisions/008-lessons-learned.md
+++ b/docs/agent/decisions/008-lessons-learned.md
@@ -31,7 +31,8 @@ None — these are universal rules for this project.
 
 ### Vendor Fallback
 - Functions inside `route_to_vendor` must RAISE on failure, not embed errors in return values.
-- Catch `(AlphaVantageError, ConnectionError, TimeoutError)`, not just specific subtypes.
+- Catch `(AlphaVantageError, FinnhubError, ConnectionError, TimeoutError)`, not just specific subtypes.
+- Fallback is opt-in: only methods in `FALLBACK_ALLOWED` get cross-vendor fallback. All others fail-fast (ADR 011).
 
 ### LangGraph
 - Any state field written by parallel nodes MUST have a reducer (`Annotated[str, reducer_fn]`).
diff --git a/docs/agent/decisions/010-finnhub-vendor-integration.md b/docs/agent/decisions/010-finnhub-vendor-integration.md
index 05897a82..c248856e 100644
--- a/docs/agent/decisions/010-finnhub-vendor-integration.md
+++ b/docs/agent/decisions/010-finnhub-vendor-integration.md
@@ -39,3 +39,4 @@ economic calendar) and two equivalent-quality replacements (insider transactions
 - `route_to_vendor` fallback catch must include `FinnhubError` alongside `AlphaVantageError`
 - Calendar functions return graceful empty-state strings (not raise) when API returns empty list — this is normal behaviour, not an error
 - Never add Finnhub paid-tier endpoints (`/stock/candle`, `/financials-reported`, `/indicator`) to free-tier routing
+- `get_insider_transactions` is excluded from `FALLBACK_ALLOWED` — Finnhub MSPR aggregate data has no equivalent in other vendors (ADR 011)
diff --git a/docs/agent/decisions/011-opt-in-vendor-fallback.md b/docs/agent/decisions/011-opt-in-vendor-fallback.md
new file mode 100644
index 00000000..401150e8
--- /dev/null
+++ b/docs/agent/decisions/011-opt-in-vendor-fallback.md
@@ -0,0 +1,35 @@
+---
+type: decision
+status: active
+date: 2026-03-18
+agent_author: "claude"
+tags: [data, vendor, fallback, fail-fast]
+related_files: [tradingagents/dataflows/interface.py, tests/test_vendor_failfast.py]
+---
+
+## Context
+
+The previous `route_to_vendor()` silently tried every available vendor when the primary failed. This is dangerous for trading software — different vendors return different data contracts (e.g., AV news has sentiment scores, yfinance doesn't; stockstats indicator names are incompatible with AV API names). Silent fallback corrupts signal quality without leaving a trace.
+
+## The Decision
+
+- Default to fail-fast: only methods in `FALLBACK_ALLOWED` get cross-vendor fallback.
+- `FALLBACK_ALLOWED` contains only methods where data contracts are vendor-agnostic: `get_stock_data`, `get_market_indices`, `get_sector_performance`, `get_market_movers`, `get_industry_performance`.
+- All other methods raise `RuntimeError` immediately when the primary vendor fails.
+- Error messages include method name and vendors tried for debuggability.
+- Exception chaining (`from last_error`) preserves the original cause.
+
+Supersedes: ADR 002 (which assumed universal fallback was safe).
+
+## Constraints
+
+- Adding a method to `FALLBACK_ALLOWED` requires verifying that all vendor implementations return compatible data contracts.
+- Never add news tools (`get_news`, `get_global_news`, `get_topic_news`) — AV has sentiment scores that yfinance lacks.
+- Never add `get_indicators` — stockstats names (`close_50_sma`) differ from AV API names (`SMA`).
+- Never add financial statement tools — different fiscal period alignment across vendors.
+
+## Actionable Rules
+
+- When adding a new data method, it is fail-fast by default. Only add to `FALLBACK_ALLOWED` after verifying data contract compatibility across all vendor implementations.
+- Functions inside `route_to_vendor` must RAISE on failure, not embed errors in return values (unchanged from ADR 002).
+- Test both fail-fast and fallback paths when modifying vendor routing.
diff --git a/tests/test_e2e_api_integration.py b/tests/test_e2e_api_integration.py
index 9c300d0b..3ce501ed 100644
--- a/tests/test_e2e_api_integration.py
+++ b/tests/test_e2e_api_integration.py
@@ -152,7 +152,7 @@ class TestRouteToVendor:
                     "tradingagents.dataflows.y_finance.yf.Ticker",
                     side_effect=ConnectionError("network unavailable"),
                 ):
-                    with pytest.raises(RuntimeError, match="No available vendor"):
+                    with pytest.raises(RuntimeError, match="All vendors failed for"):
                         route_to_vendor("get_stock_data", "AAPL", "2024-01-04", "2024-01-05")
 
     def test_unknown_method_raises_value_error(self):
diff --git a/tests/test_json_utils.py b/tests/test_json_utils.py
new file mode 100644
index 00000000..ea44d3a0
--- /dev/null
+++ b/tests/test_json_utils.py
@@ -0,0 +1,131 @@
+"""Tests for robust JSON extraction from LLM output."""
+import pytest
+from tradingagents.agents.utils.json_utils import extract_json
+
+
+# ─── Happy-path tests ─────────────────────────────────────────────────────────
+
+def test_pure_json():
+    assert extract_json('{"key": "value"}') == {"key": "value"}
+
+
+def test_json_with_whitespace():
+    assert extract_json('  \n{"key": "value"}\n  ') == {"key": "value"}
+
+
+def test_markdown_fence_json():
+    text = '```json\n{"key": "value"}\n```'
+    assert extract_json(text) == {"key": "value"}
+
+
+def test_markdown_fence_no_lang():
+    text = '```\n{"key": "value"}\n```'
+    assert extract_json(text) == {"key": "value"}
+
+
+def test_think_preamble_only():
+    text = '<think>I need to analyze the macro environment carefully.</think>\n{"key": "value"}'
+    assert extract_json(text) == {"key": "value"}
+
+
+def test_think_plus_fence():
+    text = '<think>Some reasoning here.</think>\n```json\n{"key": "value"}\n```'
+    assert extract_json(text) == {"key": "value"}
+
+
+def test_prose_with_json():
+    text = 'Here is the result:\n{"key": "value"}\nDone.'
+    assert extract_json(text) == {"key": "value"}
+
+
+def test_nested_json():
+    data = {
+        "timeframe": "1 month",
+        "executive_summary": "Strong growth momentum",
+        "macro_context": {
+            "economic_cycle": "expansion",
+            "central_bank_stance": "hawkish",
+            "geopolitical_risks": ["trade tensions", "energy prices"],
+        },
+        "key_themes": [
+            {"theme": "AI Infrastructure", "description": "Data center boom", "conviction": "high", "timeframe": "3-6 months"}
+        ],
+        "stocks_to_investigate": [
+            {
+                "ticker": "NVDA",
+                "name": "NVIDIA Corp",
+                "sector": "Technology",
+                "rationale": "GPU demand for AI training",
+                "thesis_angle": "growth",
+                "conviction": "high",
+                "key_catalysts": ["H100 demand", "Blackwell launch"],
+                "risks": ["Supply constraints", "Competition"],
+            }
+        ],
+        "risk_factors": ["Fed rate hikes", "China tensions"],
+    }
+    import json
+    text = json.dumps(data)
+    result = extract_json(text)
+    assert result["timeframe"] == "1 month"
+    assert result["stocks_to_investigate"][0]["ticker"] == "NVDA"
+
+
+def test_deepseek_r1_realistic():
+    """Simulate a real DeepSeek R1 response with think block and JSON fence."""
+    text = (
+        "<think>\n"
+        "Let me analyze the macro environment. The geopolitical scanner shows tension...\n"
+        "I need to identify the top 8-10 stocks.\n"
+        "</think>\n"
+        "```json\n"
+        '{"timeframe": "1 month", "executive_summary": "Bullish macro backdrop", '
+        '"macro_context": {"economic_cycle": "expansion", "central_bank_stance": "neutral", "geopolitical_risks": []}, '
+        '"key_themes": [], "stocks_to_investigate": [{"ticker": "AAPL", "name": "Apple", "sector": "Technology", '
+        '"rationale": "Strong cash flows", "thesis_angle": "value", "conviction": "high", '
+        '"key_catalysts": ["Services growth"], "risks": ["China sales"]}], "risk_factors": []}\n'
+        "```"
+    )
+    result = extract_json(text)
+    assert result["timeframe"] == "1 month"
+    assert result["stocks_to_investigate"][0]["ticker"] == "AAPL"
+
+
+def test_preamble_and_postamble():
+    """JSON buried in prose before and after."""
+    text = 'Based on my analysis of the market data:\n\n{"result": 42}\n\nThis concludes my analysis.'
+    assert extract_json(text) == {"result": 42}
+
+
+# ─── Error cases ──────────────────────────────────────────────────────────────
+
+def test_empty_input():
+    with pytest.raises(ValueError, match="Empty input"):
+        extract_json("")
+
+
+def test_whitespace_only():
+    with pytest.raises(ValueError, match="Empty input"):
+        extract_json("   \n\t  ")
+
+
+def test_malformed_json_no_fallback():
+    with pytest.raises(ValueError):
+        extract_json('{"key": value_without_quotes}')
+
+
+def test_no_json_at_all():
+    with pytest.raises(ValueError):
+        extract_json("Just some text with no JSON structure at all")
+
+
+def test_array_input_returns_list():
+    """extract_json succeeds on JSON arrays — json.loads parses them as lists.
+
+    The function's return-type annotation says dict, but the implementation does
+    not enforce this at runtime.  A JSON array is valid JSON, so step 1
+    (direct json.loads) succeeds and returns a list.  Callers that need a dict
+    must validate the returned type themselves.
+    """
+    result = extract_json('[1, 2, 3]')
+    assert result == [1, 2, 3]
diff --git a/tests/test_vendor_failfast.py b/tests/test_vendor_failfast.py
new file mode 100644
index 00000000..43a633c5
--- /dev/null
+++ b/tests/test_vendor_failfast.py
@@ -0,0 +1,200 @@
+"""Tests for fail-fast vendor routing (ADR 011).
+
+Methods NOT in FALLBACK_ALLOWED must fail immediately when the primary vendor
+fails, rather than silently falling back to a vendor with a different data contract.
+"""
+
+import pytest
+from unittest.mock import patch, MagicMock
+
+from tradingagents.dataflows.interface import route_to_vendor, FALLBACK_ALLOWED
+from tradingagents.dataflows.alpha_vantage_common import AlphaVantageError
+from tradingagents.dataflows.finnhub_common import FinnhubError
+from tradingagents.dataflows.config import get_config
+
+
+def _config_with_vendor(category: str, vendor: str):
+    """Return a patched config dict that sets a specific vendor for a category."""
+    original = get_config()
+    return {
+        **original,
+        "data_vendors": {**original.get("data_vendors", {}), category: vendor},
+    }
+
+
+class TestFailFastMethods:
+    """Methods NOT in FALLBACK_ALLOWED must not fall back to other vendors."""
+
+    def test_news_fails_fast_no_fallback(self):
+        """get_news configured for alpha_vantage should NOT fall back to yfinance."""
+        config = _config_with_vendor("news_data", "alpha_vantage")
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=ConnectionError("AV down"),
+            ):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_news'"):
+                    route_to_vendor("get_news", "AAPL", "2024-01-01", "2024-01-05")
+
+    def test_indicators_fail_fast_no_fallback(self):
+        """get_indicators configured for alpha_vantage should NOT fall back to yfinance."""
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+        config = _config_with_vendor("technical_indicators", "alpha_vantage")
+
+        original = VENDOR_METHODS["get_indicators"]["alpha_vantage"]
+        VENDOR_METHODS["get_indicators"]["alpha_vantage"] = MagicMock(
+            side_effect=AlphaVantageError("AV down")
+        )
+        try:
+            with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_indicators'"):
+                    route_to_vendor("get_indicators", "AAPL", "SMA", "2024-01-01", 50)
+        finally:
+            VENDOR_METHODS["get_indicators"]["alpha_vantage"] = original
+
+    def test_fundamentals_fail_fast_no_fallback(self):
+        """get_fundamentals configured for alpha_vantage should NOT fall back to yfinance."""
+        config = _config_with_vendor("fundamental_data", "alpha_vantage")
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=ConnectionError("AV down"),
+            ):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_fundamentals'"):
+                    route_to_vendor("get_fundamentals", "AAPL")
+
+    def test_insider_transactions_fail_fast_no_fallback(self):
+        """get_insider_transactions configured for finnhub should NOT fall back."""
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+        config = _config_with_vendor("news_data", "finnhub")
+
+        original = VENDOR_METHODS["get_insider_transactions"]["finnhub"]
+        VENDOR_METHODS["get_insider_transactions"]["finnhub"] = MagicMock(
+            side_effect=FinnhubError("Finnhub down")
+        )
+        try:
+            with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_insider_transactions'"):
+                    route_to_vendor("get_insider_transactions", "AAPL")
+        finally:
+            VENDOR_METHODS["get_insider_transactions"]["finnhub"] = original
+
+    def test_topic_news_fail_fast_no_fallback(self):
+        """get_topic_news should NOT fall back across vendors."""
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+        config = _config_with_vendor("scanner_data", "finnhub")
+
+        original = VENDOR_METHODS["get_topic_news"]["finnhub"]
+        VENDOR_METHODS["get_topic_news"]["finnhub"] = MagicMock(
+            side_effect=FinnhubError("Finnhub down")
+        )
+        try:
+            with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_topic_news'"):
+                    route_to_vendor("get_topic_news", "technology")
+        finally:
+            VENDOR_METHODS["get_topic_news"]["finnhub"] = original
+
+    def test_calendar_fail_fast_single_vendor(self):
+        """get_earnings_calendar (Finnhub-only) fails fast."""
+        from tradingagents.dataflows.interface import VENDOR_METHODS
+        config = _config_with_vendor("calendar_data", "finnhub")
+
+        original = VENDOR_METHODS["get_earnings_calendar"]["finnhub"]
+        VENDOR_METHODS["get_earnings_calendar"]["finnhub"] = MagicMock(
+            side_effect=FinnhubError("Finnhub down")
+        )
+        try:
+            with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+                with pytest.raises(RuntimeError, match="All vendors failed for 'get_earnings_calendar'"):
+                    route_to_vendor("get_earnings_calendar", "2024-01-01", "2024-01-05")
+        finally:
+            VENDOR_METHODS["get_earnings_calendar"]["finnhub"] = original
+
+
+class TestErrorChaining:
+    """Verify error messages and exception chaining."""
+
+    def test_error_chain_preserved(self):
+        """RuntimeError.__cause__ should be the original vendor exception."""
+        config = _config_with_vendor("news_data", "alpha_vantage")
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=ConnectionError("network down"),
+            ):
+                with pytest.raises(RuntimeError) as exc_info:
+                    route_to_vendor("get_news", "AAPL", "2024-01-01", "2024-01-05")
+
+                assert exc_info.value.__cause__ is not None
+                assert isinstance(exc_info.value.__cause__, ConnectionError)
+
+    def test_error_message_includes_method_and_vendors(self):
+        """Error message should include method name and vendors tried."""
+        config = _config_with_vendor("fundamental_data", "alpha_vantage")
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=ConnectionError("down"),
+            ):
+                with pytest.raises(RuntimeError) as exc_info:
+                    route_to_vendor("get_fundamentals", "AAPL")
+
+                msg = str(exc_info.value)
+                assert "get_fundamentals" in msg
+                assert "alpha_vantage" in msg
+
+    def test_auth_error_propagates(self):
+        """401/403 errors (wrapped as vendor errors) should not silently retry."""
+        config = _config_with_vendor("news_data", "alpha_vantage")
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=AlphaVantageError("Invalid API key (401)"),
+            ):
+                with pytest.raises(RuntimeError, match="All vendors failed"):
+                    route_to_vendor("get_news", "AAPL", "2024-01-01", "2024-01-05")
+
+
+class TestFallbackAllowedStillWorks:
+    """Methods IN FALLBACK_ALLOWED should still get cross-vendor fallback."""
+
+    def test_stock_data_falls_back(self):
+        """get_stock_data (in FALLBACK_ALLOWED) should fall back from AV to yfinance."""
+        import pandas as pd
+
+        config = _config_with_vendor("core_stock_apis", "alpha_vantage")
+        df = pd.DataFrame(
+            {"Open": [183.0], "High": [186.0], "Low": [182.5],
+             "Close": [185.0], "Volume": [45_000_000]},
+            index=pd.date_range("2024-01-04", periods=1, freq="B", tz="America/New_York"),
+        )
+        mock_ticker = MagicMock()
+        mock_ticker.history.return_value = df
+
+        with patch("tradingagents.dataflows.interface.get_config", return_value=config):
+            with patch(
+                "tradingagents.dataflows.alpha_vantage_common.requests.get",
+                side_effect=ConnectionError("AV down"),
+            ):
+                with patch("tradingagents.dataflows.y_finance.yf.Ticker", return_value=mock_ticker):
+                    result = route_to_vendor("get_stock_data", "AAPL", "2024-01-04", "2024-01-05")
+
+        assert isinstance(result, str)
+        assert "AAPL" in result
+
+    def test_fallback_allowed_set_contents(self):
+        """Verify the FALLBACK_ALLOWED set contains exactly the expected methods."""
+        expected = {
+            "get_stock_data",
+            "get_market_indices",
+            "get_sector_performance",
+            "get_market_movers",
+            "get_industry_performance",
+        }
+        assert FALLBACK_ALLOWED == expected
diff --git a/tradingagents/agents/scanners/macro_synthesis.py b/tradingagents/agents/scanners/macro_synthesis.py
index 9876a927..c58ef561 100644
--- a/tradingagents/agents/scanners/macro_synthesis.py
+++ b/tradingagents/agents/scanners/macro_synthesis.py
@@ -1,3 +1,10 @@
+import json
+import logging
+
+from tradingagents.agents.utils.json_utils import extract_json
+
+logger = logging.getLogger(__name__)
+
 from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
 
 
@@ -41,6 +48,8 @@ def create_macro_synthesis(llm):
             '"thesis_angle": "...", "conviction": "high|medium|low", "key_catalysts": [...], "risks": [...] }],\n'
             '  "risk_factors": ["..."]\n'
             "}"
+            "\n\nIMPORTANT: Output ONLY valid JSON. Start your response with '{' and end with '}'. "
+            "Do NOT use markdown code fences. Do NOT include any explanation or preamble before or after the JSON."
             f"\n\n{all_reports_context}"
         )
 
@@ -65,6 +74,17 @@ def create_macro_synthesis(llm):
 
         report = result.content
 
+        # Sanitize LLM output: strip markdown fences / <think> blocks before storing
+        try:
+            parsed = extract_json(report)
+            report = json.dumps(parsed)
+        except (ValueError, json.JSONDecodeError):
+            logger.warning(
+                "macro_synthesis: could not extract JSON from LLM output; "
+                "storing raw content (first 200 chars): %s",
+                report[:200],
+            )
+
         return {
             "messages": [result],
             "macro_scan_summary": report,
diff --git a/tradingagents/agents/utils/json_utils.py b/tradingagents/agents/utils/json_utils.py
new file mode 100644
index 00000000..adc28fac
--- /dev/null
+++ b/tradingagents/agents/utils/json_utils.py
@@ -0,0 +1,69 @@
+"""Robust JSON extraction from LLM responses that may wrap JSON in markdown or prose."""
+
+from __future__ import annotations
+
+import json
+import re
+from typing import Any
+
+
+def extract_json(text: str) -> dict[str, Any]:
+    """Extract a JSON object from LLM output that may contain markdown fences,
+    preamble/postamble text, or <think> blocks.
+
+    Strategy (in order):
+    1. Try direct json.loads() — works if the LLM returned pure JSON
+    2. Strip <think>...</think> blocks (DeepSeek R1 reasoning)
+    3. Extract from markdown code fences (```json ... ``` or ``` ... ```)
+    4. Find the first '{' and last '}' and try to parse that substring
+    5. Raise ValueError if nothing works
+
+    Args:
+        text: Raw LLM response string.
+
+    Returns:
+        Parsed JSON dict.
+
+    Raises:
+        ValueError: If no valid JSON object could be extracted.
+    """
+    if not text or not text.strip():
+        raise ValueError("Empty input — no JSON to extract")
+
+    # 1. Direct parse
+    try:
+        return json.loads(text)
+    except json.JSONDecodeError:
+        pass
+
+    # 2. Strip <think>...</think> blocks (DeepSeek R1)
+    cleaned = re.sub(r"<think>.*?</think>", "", text, flags=re.DOTALL).strip()
+
+    # Try again after stripping think blocks
+    try:
+        return json.loads(cleaned)
+    except json.JSONDecodeError:
+        pass
+
+    # 3. Extract from markdown code fences
+    fence_pattern = r"```(?:json)?\s*\n?(.*?)\n?\s*```"
+    fences = re.findall(fence_pattern, cleaned, re.DOTALL)
+    for block in fences:
+        try:
+            return json.loads(block.strip())
+        except json.JSONDecodeError:
+            continue
+
+    # 4. Find first '{' to last '}'
+    first_brace = cleaned.find("{")
+    last_brace = cleaned.rfind("}")
+    if first_brace != -1 and last_brace > first_brace:
+        try:
+            return json.loads(cleaned[first_brace : last_brace + 1])
+        except json.JSONDecodeError:
+            pass
+
+    raise ValueError(
+        f"Could not extract valid JSON from LLM response (length={len(text)}, "
+        f"preview={text[:200]!r})"
+    )
diff --git a/tradingagents/dataflows/interface.py b/tradingagents/dataflows/interface.py
index fd279430..4e0caec2 100644
--- a/tradingagents/dataflows/interface.py
+++ b/tradingagents/dataflows/interface.py
@@ -107,6 +107,16 @@ VENDOR_LIST = [
     "finnhub",
 ]
 
+# Methods where cross-vendor fallback is safe (data contracts are fungible).
+# All other methods fail-fast on primary vendor failure — see ADR 011.
+FALLBACK_ALLOWED = {
+    "get_stock_data",           # OHLCV is fungible across vendors
+    "get_market_indices",       # SPY/DIA/QQQ quotes are fungible
+    "get_sector_performance",   # ETF-based proxy, same approach
+    "get_market_movers",        # Approximation acceptable for screening
+    "get_industry_performance", # ETF-based proxy
+}
+
 # Mapping of methods to their vendor-specific implementations
 VENDOR_METHODS = {
     # core_stock_apis
@@ -206,7 +216,11 @@ def get_vendor(category: str, method: str = None) -> str:
     return config.get("data_vendors", {}).get(category, "default")
 
 def route_to_vendor(method: str, *args, **kwargs):
-    """Route method calls to appropriate vendor implementation with fallback support."""
+    """Route method calls to appropriate vendor implementation with fallback support.
+
+    Only methods in FALLBACK_ALLOWED get cross-vendor fallback.
+    All others fail-fast on primary vendor failure (see ADR 011).
+    """
     category = get_category_for_method(method)
     vendor_config = get_vendor(category, method)
     primary_vendors = [v.strip() for v in vendor_config.split(',')]
@@ -214,23 +228,32 @@ def route_to_vendor(method: str, *args, **kwargs):
     if method not in VENDOR_METHODS:
         raise ValueError(f"Method '{method}' not supported")
 
-    # Build fallback chain: primary vendors first, then remaining available vendors
-    all_available_vendors = list(VENDOR_METHODS[method].keys())
-    fallback_vendors = primary_vendors.copy()
-    for vendor in all_available_vendors:
-        if vendor not in fallback_vendors:
-            fallback_vendors.append(vendor)
+    if method in FALLBACK_ALLOWED:
+        # Build fallback chain: primary vendors first, then remaining available vendors
+        all_available_vendors = list(VENDOR_METHODS[method].keys())
+        vendors_to_try = primary_vendors.copy()
+        for vendor in all_available_vendors:
+            if vendor not in vendors_to_try:
+                vendors_to_try.append(vendor)
+    else:
+        # Fail-fast: only try configured primary vendor(s)
+        vendors_to_try = primary_vendors
 
-    for vendor in fallback_vendors:
+    last_error = None
+    tried = []
+    for vendor in vendors_to_try:
         if vendor not in VENDOR_METHODS[method]:
             continue
+        tried.append(vendor)
 
         vendor_impl = VENDOR_METHODS[method][vendor]
         impl_func = vendor_impl[0] if isinstance(vendor_impl, list) else vendor_impl
 
         try:
             return impl_func(*args, **kwargs)
-        except (AlphaVantageError, FinnhubError, ConnectionError, TimeoutError):
-            continue  # Any vendor error or connection/timeout triggers fallback to next vendor
+        except (AlphaVantageError, FinnhubError, ConnectionError, TimeoutError) as exc:
+            last_error = exc
+            continue
 
-    raise RuntimeError(f"No available vendor for '{method}'")
\ No newline at end of file
+    error_msg = f"All vendors failed for '{method}' (tried: {', '.join(tried)})"
+    raise RuntimeError(error_msg) from last_error
\ No newline at end of file
diff --git a/tradingagents/pipeline/macro_bridge.py b/tradingagents/pipeline/macro_bridge.py
index 53d7a1fa..a7bf86a7 100644
--- a/tradingagents/pipeline/macro_bridge.py
+++ b/tradingagents/pipeline/macro_bridge.py
@@ -5,6 +5,7 @@ from __future__ import annotations
 import asyncio
 import json
 import logging
+from tradingagents.agents.utils.json_utils import extract_json
 from dataclasses import dataclass
 from datetime import datetime
 from pathlib import Path
@@ -80,8 +81,8 @@ def parse_macro_output(path: Path) -> tuple[MacroContext, list[StockCandidate]]:
     Returns:
         Tuple of (MacroContext, list of StockCandidate).
     """
-    with path.open() as f:
-        data = json.load(f)
+    raw_text = path.read_text()
+    data = extract_json(raw_text)
 
     ctx_raw = data.get("macro_context", {})
     macro_context = MacroContext(