diff --git a/session_memory/detect/signals.py b/session_memory/detect/signals.py
index f7b11be..f28839d 100644
--- a/session_memory/detect/signals.py
+++ b/session_memory/detect/signals.py
@@ -156,10 +156,28 @@ def sig_tool_thrash(digest, ctx) -> list[Signal]:
     return []
 
 
+def sig_recurring_error(digest, ctx) -> list[Signal]:
+    """Problem: a normalized error fingerprint (WP-0006) — one signal per distinct
+    error in the session, so the same error across sessions/repos/flavors clusters
+    into a candidate root-cause pattern (locus = fingerprint, magnitude = in-session
+    occurrences). This is the content-level 'why', not just a coarse error count.
+    """
+    out: list[Signal] = []
+    for snip in digest.get("error_snippets", []) or []:
+        fp = snip.get("fingerprint")
+        if not fp:
+            continue
+        out.append(_base(digest, "recurring_error", PROBLEM, fp, float(snip.get("count", 1)),
+                         sample=snip.get("sample", ""), tool=snip.get("tool"),
+                         occurrences=snip.get("count", 1)))
+    return out
+
+
 EXTRACTORS: list[Callable] = [
     sig_retry_storm, sig_repeated_errors, sig_budget_overrun, sig_abandoned,
     sig_clean_pass, sig_error_then_recovery,
     sig_infra_overhead, sig_schema_thrash, sig_tool_thrash,
+    sig_recurring_error,
 ]
 
 
diff --git a/tests/test_detect_recurring_error.py b/tests/test_detect_recurring_error.py
new file mode 100644
index 0000000..437ff1e
--- /dev/null
+++ b/tests/test_detect_recurring_error.py
@@ -0,0 +1,59 @@
+"""Recurring-error signal + clustering (WP-0006 T02)."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from session_memory.detect.cluster import cluster  # noqa: E402
+from session_memory.detect.signals import (  # noqa: E402
+    extract_signals,
+    sig_recurring_error,
+)
+
+
+def _digest(uid, repo, flavor="claude", snippets=None):
+    return {
+        "session_uid": uid, "flavor": flavor, "repo": repo, "outcome": "success",
+        "cost": {"input_tokens": 1, "output_tokens": 1},
+        "markers": {"errors": 0, "retries": 0, "test_runs": 0},
+        "tool_histogram": {}, "error_snippets": snippets or [],
+    }
+
+
+_FP = "modulenotfounderror: no module named 'foo' at <path>:<n>"
+
+
+def test_signal_per_distinct_fingerprint():
+    d = _digest("claude:a", "r1", snippets=[
+        {"fingerprint": _FP, "sample": "ModuleNotFoundError ...", "count": 3, "tool": "Bash"},
+        {"fingerprint": "keyerror: <str>", "sample": "KeyError", "count": 1, "tool": None},
+    ])
+    sigs = sig_recurring_error(d, {})
+    assert len(sigs) == 2
+    top = [s for s in sigs if s.locus == _FP][0]
+    assert top.type == "recurring_error"
+    assert top.magnitude == 3.0
+    assert top.detail["sample"].startswith("ModuleNotFound")
+
+
+def test_clusters_across_sessions_and_flavors():
+    # same fingerprint in a claude and a grok session -> cross-flavor candidate
+    digs = [
+        _digest("claude:a", "r1", "claude",
+                [{"fingerprint": _FP, "sample": "ModuleNotFoundError", "count": 2, "tool": "Bash"}]),
+        _digest("grok:b", "r2", "grok",
+                [{"fingerprint": _FP, "sample": "ModuleNotFoundError", "count": 1, "tool": None}]),
+    ]
+    signals = extract_signals(digs)
+    pats = cluster([s for s in signals if s.type == "recurring_error"], min_frequency=2)
+    assert len(pats) == 1
+    p = pats[0]
+    assert p.signal_type == "recurring_error"
+    assert p.cross_flavor is True
+    assert sorted(p.flavors) == ["claude", "grok"]
+    assert p.frequency == 2
+
+
+def test_no_snippets_no_signal():
+    assert sig_recurring_error(_digest("claude:a", "r1"), {}) == []
diff --git a/workplans/AGENTIC-WP-0006-error-body-mining.md b/workplans/AGENTIC-WP-0006-error-body-mining.md
index aee0adf..9c34e7a 100644
--- a/workplans/AGENTIC-WP-0006-error-body-mining.md
+++ b/workplans/AGENTIC-WP-0006-error-body-mining.md
@@ -48,7 +48,7 @@ sessions with repeated and varied errors.
 
 ```task
 id: AGENTIC-WP-0006-T02
-status: todo
+status: done
 priority: high
 state_hub_task_id: "1a41b6f5-48bc-4080-bd18-94f2186ef566"
 ```