diff --git a/tests/test_active_board_routing.py b/tests/test_active_board_routing.py
new file mode 100644
index 000000000..2ea37059a
--- /dev/null
+++ b/tests/test_active_board_routing.py
@@ -0,0 +1,183 @@
+"""Offline routing consistency only; no live board, custody or status claims.
+
+Proposed path: tests/test_active_board_routing.py. The canonical destination is
+read from AGENTS.md, not hard-coded. Scope is the current simple inline-link
+labels in RESEARCH_INDEX.md; this is not a general Markdown/HTML parser.
+Historical links are untouched. Matching stale documents can still agree:
+consistency does not establish the live board, access or authorisation.
+"""
+from pathlib import Path
+import re
+import unittest
+
+ROOT = Path(__file__).resolve().parents[1]
+ISSUE_PREFIX = "https://github.com/d6g8k5htny-coder/main/issues/"
+LINK = re.compile(r"(?<!!)\[([^\]\n]+)\]\(([^)\n]*)\)")
+CANONICAL = re.compile(r"Agent Message Board #([1-9][0-9]*)", re.I)
+ACTIVE = re.compile(r"(?:active|current) Agent Message Board, main #([1-9][0-9]*)", re.I)
+
+
+def visible_links(text):
+    """Read simple inline links outside top-level backtick/tilde fences."""
+    fence = None
+    for number, line in enumerate(text.splitlines(), 1):
+        token = re.match(r"^ {0,3}(`{3,}|~{3,})(.*)$", line)
+        if fence is not None:
+            if (token and token[1][0] == fence[0]
+                    and len(token[1]) >= len(fence) and not token[2].strip()):
+                fence = None
+            continue
+        if token:
+            fence = token[1]
+            continue
+        for match in LINK.finditer(line):
+            yield number, " ".join(match[1].split()), match[2]
+
+
+def route_problems(agents, research_index):
+    canonical = [(line, CANONICAL.fullmatch(label), target)
+                 for line, label, target in visible_links(agents)
+                 if CANONICAL.fullmatch(label)]
+    if len(canonical) != 1:
+        return ["AGENTS.md: expected exactly one canonical board link"]
+    line, label, target = canonical[0]
+    expected = ISSUE_PREFIX + label[1]
+    if target != expected:
+        return [f"AGENTS.md:{line}: canonical label/target mismatch"]
+    problems = []
+    count = 0
+    for line, label, target in visible_links(research_index):
+        active = ACTIVE.fullmatch(label)
+        if not active:
+            continue
+        count += 1
+        if active[1] != canonical[0][1][1] or target != expected:
+            problems.append(f"docs/RESEARCH_INDEX.md:{line}: active board mismatch")
+    if not count:
+        problems.append("docs/RESEARCH_INDEX.md: no qualifying active board links")
+    return problems
+
+
+class RoutingContractTests(unittest.TestCase):
+    def setUp(self):
+        self.agents = self.canonical(475)
+        self.good = self.active(475)
+
+    @staticmethod
+    def canonical(number):
+        return f"[Agent Message Board #{number}]({ISSUE_PREFIX}{number})\n"
+
+    @staticmethod
+    def active(number, word="active"):
+        return f"[{word} Agent Message Board, main #{number}]({ISSUE_PREFIX}{number})\n"
+
+    def test_matching_active_and_current(self):
+        self.assertEqual(route_problems(self.agents, self.good + self.active(475, "current")), [])
+
+    def test_stale_active_board_is_detected(self):
+        self.assertEqual(route_problems(self.agents, self.active(419)),
+                         ["docs/RESEARCH_INDEX.md:1: active board mismatch"])
+
+    def test_label_and_target_are_both_checked(self):
+        for source in (self.good.replace("#475]", "#419]"),
+                       self.good.replace("/475)", "/419)")):
+            with self.subTest(source=source):
+                self.assertEqual(len(route_problems(self.agents, source)), 1)
+
+    def test_all_active_links_are_checked(self):
+        self.assertEqual(route_problems(self.agents, self.good + self.active(419)),
+                         ["docs/RESEARCH_INDEX.md:2: active board mismatch"])
+
+    def test_historical_links_and_comment_anchors_remain_allowed(self):
+        history = f"[#419]({ISSUE_PREFIX}419) [working guidance]({ISSUE_PREFIX}229#issuecomment-6038554880)\n"
+        self.assertEqual(route_problems(self.agents, self.good + history), [])
+
+    def test_fenced_examples_are_ignored(self):
+        for opener, closer in (("```md", "```"), ("~~~~text", "~~~~")):
+            with self.subTest(opener=opener):
+                example = opener + "\n" + self.active(419) + closer + "\n"
+                self.assertEqual(route_problems(self.agents, example + self.good), [])
+
+    def test_shorter_or_different_fence_does_not_close_example(self):
+        example = "````md\n```\n~~~\n" + self.active(419) + "````\n"
+        self.assertEqual(route_problems(self.agents, example + self.good), [])
+
+    def test_fenced_canonical_example_does_not_add_ambiguity(self):
+        example = "```md\n" + self.canonical(419) + "```\n"
+        self.assertEqual(route_problems(self.agents + example, self.good), [])
+
+    def test_canonical_link_must_exist_and_be_unique(self):
+        for agents in ("", self.agents + self.agents, self.agents + self.canonical(419)):
+            with self.subTest(agents=agents):
+                self.assertEqual(route_problems(agents, self.good),
+                                 ["AGENTS.md: expected exactly one canonical board link"])
+
+    def test_canonical_label_target_mismatch_is_refused(self):
+        agents = self.agents.replace("/475)", "/419)")
+        self.assertEqual(route_problems(agents, self.good),
+                         ["AGENTS.md:1: canonical label/target mismatch"])
+
+    def test_missing_active_label_is_not_vacuous_success(self):
+        for index in ("", f"[#419]({ISSUE_PREFIX}419)", "```\n" + self.good + "```\n"):
+            with self.subTest(index=index):
+                self.assertEqual(route_problems(self.agents, index),
+                                 ["docs/RESEARCH_INDEX.md: no qualifying active board links"])
+
+    def test_wrong_destination_variants_are_refused(self):
+        for target in (ISSUE_PREFIX + "475#issuecomment-1", ISSUE_PREFIX + "475?x=1",
+                       ISSUE_PREFIX.replace("/main/", "/Math-/") + "475",
+                       ISSUE_PREFIX.replace("github.com", "example.com") + "475",
+                       ISSUE_PREFIX.replace("https:", "http:") + "475"):
+            with self.subTest(target=target):
+                index = f"[active Agent Message Board, main #475]({target})"
+                self.assertEqual(len(route_problems(self.agents, index)), 1)
+
+    def test_future_rollover_needs_no_hardcoded_board_update(self):
+        self.assertEqual(route_problems(self.canonical(900), self.active(900)), [])
+        self.assertEqual(len(route_problems(self.canonical(900), self.good)), 1)
+
+    def test_case_and_whitespace_normalization(self):
+        index = self.good.replace("active Agent Message Board", "CURRENT  agent message board")
+        self.assertEqual(route_problems(self.agents, index), [])
+
+    def test_image_is_not_an_active_navigation_link(self):
+        self.assertEqual(route_problems(self.agents, "!" + self.good),
+                         ["docs/RESEARCH_INDEX.md: no qualifying active board links"])
+
+    def test_fence_closes_only_with_same_character(self):
+        example = "```md\n~~~\n" + self.active(419) + "```\n"
+        self.assertEqual(route_problems(self.agents, example + self.good), [])
+
+    def test_fence_with_info_string_does_not_close(self):
+        example = "```md\n```text\n" + self.active(419) + "```\n"
+        self.assertEqual(route_problems(self.agents, example + self.good), [])
+
+    def test_four_space_indent_is_not_a_fence(self):
+        index = "    ```\n" + self.active(419)
+        self.assertEqual(route_problems(self.agents, index), ["docs/RESEARCH_INDEX.md:2: active board mismatch"])
+
+    def test_only_exact_active_labels_qualify(self):
+        index = f"[see the active Agent Message Board, main #419 here]({ISSUE_PREFIX}419)\n"
+        self.assertEqual(route_problems(self.agents, self.good + index), [])
+
+    def test_only_exact_canonical_labels_qualify(self):
+        agents = self.agents + f"[the Agent Message Board #419 archive]({ISSUE_PREFIX}419)\n"
+        self.assertEqual(route_problems(agents, self.good), [])
+
+    def test_every_stale_active_link_is_reported(self):
+        self.assertEqual(route_problems(self.agents, self.active(419) + self.active(307)), ["docs/RESEARCH_INDEX.md:1: active board mismatch", "docs/RESEARCH_INDEX.md:2: active board mismatch"])
+
+    def test_canonical_label_is_case_insensitive(self):
+        agents = self.agents.replace("Agent Message Board", "agent message board")
+        self.assertEqual(route_problems(agents, self.good), [])
+
+
+class RepositoryRoutingTests(unittest.TestCase):
+    def test_research_index_matches_agent_entry(self):
+        agents = (ROOT / "AGENTS.md").read_text(encoding="utf-8")
+        index = (ROOT / "docs/RESEARCH_INDEX.md").read_text(encoding="utf-8")
+        self.assertEqual(route_problems(agents, index), [])
+
+
+if __name__ == "__main__":
+    unittest.main()