grounding: wire matched email bodies into the LP-feedback corpus

_ground_feedback_corpus now pulls matched email bodies (the richest objection
signal) alongside communications and grid notes, round-robin merged so email is
never crowded out by a flat LIMIT, per-item capped at 4000 chars to keep the local
minimize tractable on long threads, and degrading gracefully when the email tables
are absent. Email remains Tier-2-sensitive: it only ever enters the redaction
boundary, never Claude directly. Inert until Gmail capture is enrolled. Not yet
deployed (bundles into the next release with the meeting-notes work).
Test: test_ground_corpus.py.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/test_ground_corpus.py

@@ -0,0 +1,75 @@
+#!/usr/bin/env python3
+"""Test the grounding feedback corpus assembly (CRMHandler._ground_feedback_corpus).
+
+Verifies email bodies are wired in: matched-only, balanced round-robin merge across
+email/communications/grid-notes, per-item length cap on long threads, and graceful
+degradation when the email tables are absent. Synthetic data only (guardrail #9).
+Run: cd backend && python3 test_ground_corpus.py
+"""
+import os
+import sqlite3
+import sys
+import tempfile
+
+os.environ.setdefault("CRM_DB_PATH", os.path.join(tempfile.mkdtemp(), "import.db"))
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+import server  # noqa: E402
+
+corpus = server.CRMHandler._ground_feedback_corpus  # unbound; method uses only (conn, limit)
+FAILS = []
+
+
+def check(cond, msg):
+    print(("  PASS " if cond else "  FAIL ") + msg)
+    if not cond:
+        FAILS.append(msg)
+
+
+def mkdb(with_email=True):
+    db = os.path.join(tempfile.mkdtemp(), "t.db")
+    c = sqlite3.connect(db)
+    c.execute("CREATE TABLE communications(body TEXT, communication_date TEXT)")
+    c.execute("CREATE TABLE fundraising_investors(notes TEXT)")
+    c.executemany("INSERT INTO communications VALUES(?,?)", [(f"comm {i}", f"2026-01-{i+1:02d}") for i in range(5)])
+    c.executemany("INSERT INTO fundraising_investors VALUES(?)", [(f"note {i}",) for i in range(5)])
+    if with_email:
+        c.execute("CREATE TABLE emails(body_text TEXT, match_status TEXT, sent_at TEXT)")
+        c.executemany("INSERT INTO emails VALUES(?,?,?)",
+                      [(f"EMAIL {i}", "matched", f"2026-02-{i+1:02d}") for i in range(5)]
+                      + [("UNMATCHED should not appear", "unmatched", "2026-03-01")])
+    c.commit()
+    return c
+
+
+def main():
+    c = mkdb(True)
+    items = corpus(None, c, limit=9)
+    check(any(x.startswith("EMAIL") for x in items), "matched email is represented in the corpus")
+    check(all("UNMATCHED" not in x for x in items), "unmatched emails are excluded")
+    check(any(x.startswith("comm") for x in items) and any(x.startswith("note") for x in items),
+          "communications and grid notes still represented")
+    check(items[0].startswith("EMAIL") and items[1].startswith("comm") and items[2].startswith("note"),
+          "sources are round-robin balanced (email not crowded out)")
+
+    items2 = corpus(None, mkdb(False), limit=20)
+    check(len(items2) == 10 and all("EMAIL" not in x for x in items2),
+          "degrades gracefully to comms+notes when email table absent")
+
+    c3 = sqlite3.connect(os.path.join(tempfile.mkdtemp(), "t3.db"))
+    c3.execute("CREATE TABLE communications(body TEXT, communication_date TEXT)")
+    c3.execute("CREATE TABLE fundraising_investors(notes TEXT)")
+    c3.execute("CREATE TABLE emails(body_text TEXT, match_status TEXT, sent_at TEXT)")
+    c3.execute("INSERT INTO emails VALUES(?,?,?)", ("X" * 9000, "matched", "2026-02-01"))
+    c3.commit()
+    check(len(corpus(None, c3, limit=5)[0]) == 4000, "long email body capped at 4000 chars for local minimize")
+
+    if FAILS:
+        print(f"\nFAILED ({len(FAILS)})")
+        for f in FAILS:
+            print("  - " + f)
+        sys.exit(1)
+    print("\nALL PASS (email grounding corpus wiring)")
+
+
+if __name__ == "__main__":
+    main()