feat: search --hop walks FROM_FILE to Person. (#30)

Parser no longer errors; hop 1 returns File, hop 3 reaches Person.
Rebuild writes Leaf-[:FROM_FILE]->File so the walk is not empty
on a fresh index (Gitea #17).

bin/tools/kblib.py

@@ -162,6 +162,53 @@ def add_leafs(conn: ladybug.Connection, leafs: list[dict]) -> list[str]:
     return ids
 
 
+def file_id(repo: str, path: str) -> str:
+    """Stable File.id matching gitimport (`repo:path`)."""
+    return f"{repo}:{path}" if repo else path
+
+
+def link_from_file(conn: ladybug.Connection, leaf_id: str, path: str,
+                   repo: str = "", mtime: str = "") -> str:
+    """MERGE File and Leaf-[:FROM_FILE]->File so --hop 1 can walk."""
+    fid = file_id(repo, path)
+    conn.execute(
+        "MERGE (f:File {id:$id}) SET f.path=$path, f.repo=$repo, f.mtime=$mtime",
+        parameters={"id": fid, "path": path, "repo": repo, "mtime": mtime},
+    )
+    conn.execute(
+        "MATCH (l:Leaf {id:$lid}), (f:File {id:$fid}) "
+        "MERGE (l)-[:FROM_FILE]->(f)",
+        parameters={"lid": leaf_id, "fid": fid},
+    )
+    return fid
+
+
+HOP_STMTS = {
+    1: "MATCH (l:Leaf {id:$id})-[:FROM_FILE]->(f:File) RETURN f.id, f.path, 1",
+    2: ("MATCH (l:Leaf {id:$id})-[:FROM_FILE]->(f:File)-[:HAS_VERSION]->(c:Commit) "
+        "RETURN c.id, c.subject, 2"),
+    3: ("MATCH (l:Leaf {id:$id})-[:FROM_FILE]->(f:File)-[:HAS_VERSION]->(c:Commit)"
+        "-[:AUTHORED]->(p:Person) RETURN p.id, p.name, 3"),
+}
+HOP_LABELS = {1: "File", 2: "Commit", 3: "Person"}
+
+
+def hop_walk(conn: ladybug.Connection, leaf_id: str, n: int) -> list[dict]:
+    """Walk Leaf → File → Commit → Person up to n hops (max 3)."""
+    depth = min(max(int(n), 0), 3)
+    out: list[dict] = []
+    for d in range(1, depth + 1):
+        rows = conn.execute(HOP_STMTS[d], parameters={"id": leaf_id}).get_all()
+        for row in rows:
+            out.append({
+                "id": row[0],
+                "label": HOP_LABELS[d],
+                "name": row[1],
+                "depth": int(row[2]),
+            })
+    return out
+
+
 def leaf_index_names(conn: ladybug.Connection) -> set[str]:
     """Return index names on the Leaf table (e.g. {'id', 'Leaf_vec', '_PK'})."""
     rows = conn.execute("CALL SHOW_INDEXES() RETURN *").get_all()

bin/tools/test_kblib.py

@@ -161,6 +161,39 @@ class KblibTest(unittest.TestCase):
         self.assertEqual(stats["total"], 2)
         self.assertEqual(stats["by_root"], {"facts": 1, "info": 1})
 
+    def test_hop_1_returns_file_hop_3_reaches_person(self):
+        """--hop walks FROM_FILE / HAS_VERSION / AUTHORED (Gitea #17)."""
+        import gitimport
+
+        lid = kblib.upsert_leaf(
+            self.conn, text="readme hop fixture", root="info",
+            confidence="confirmed", source="README.md", source_rev="r1",
+            how="test", loc="README.md", type_="reference",
+            embedding=make_emb(0.3),
+        )
+        kblib.link_from_file(self.conn, lid, "README.md", repo="sample-repo")
+        gitimport.index_commits(self.conn, [gitimport.Commit(
+            sha="a1b2c3d",
+            author="Ada Lovelace",
+            email="ada@example.com",
+            date="2026-08-10T12:00:00Z",
+            subject="feat: first commit",
+            files=["README.md"],
+        )], "sample-repo")
+        hop1 = kblib.hop_walk(self.conn, lid, 1)
+        self.assertEqual(len(hop1), 1)
+        self.assertEqual(hop1[0]["label"], "File")
+        self.assertEqual(hop1[0]["name"], "README.md")
+        self.assertEqual(hop1[0]["depth"], 1)
+        hop3 = kblib.hop_walk(self.conn, lid, 3)
+        labels = {n["label"] for n in hop3}
+        self.assertIn("File", labels)
+        self.assertIn("Commit", labels)
+        self.assertIn("Person", labels)
+        person = [n for n in hop3 if n["label"] == "Person"][0]
+        self.assertEqual(person["name"], "Ada Lovelace")
+        self.assertEqual(person["depth"], 3)
+
 
 if __name__ == "__main__":
     unittest.main()

bin/tools/test_published_docs.py

@@ -1,7 +1,6 @@
-"""Published docs must match live commands (Gitea SoT, brain/search, no fake --hop)."""
+"""Published docs must match live commands (Gitea SoT, brain/search)."""
 from __future__ import annotations
 
-import re
 import unittest
 from pathlib import Path
 
@@ -139,24 +138,21 @@ class PublishedDocsTest(unittest.TestCase):
         skill = (ROOT / "skills" / "brain" / "SKILL.md").read_text()
         self.assertIn("`web` block", skill)
 
-    def test_docs_do_not_claim_hop_walks(self) -> None:
+    def test_docs_say_hop_walks_from_file(self) -> None:
         paths = [
             ROOT / "README.md",
             ROOT / "docs" / "design.md",
             ROOT / "skills" / "brain" / "SKILL.md",
-            ROOT / "skills" / "diataxis-docs" / "SKILL.md",
             ROOT / "docs" / "runbook.md",
             ROOT / "docs" / "README.md",
-            ROOT / "docs" / "roadmap.md",
         ]
-        # Command-style `--hop 1` / `--hop N` plus follow/walk = the old lie.
-        # Honest "not implemented" notes must not match.
-        lie = re.compile(r"--hop (?:N|1).*(?:follow|walk)", re.I | re.S)
         for path in paths:
             text = path.read_text()
-            self.assertIsNone(
-                lie.search(text),
-                f"{path.relative_to(ROOT)} still claims --hop walks the graph",
+            self.assertIn("--hop", text, f"{path.relative_to(ROOT)} must document --hop")
+            self.assertNotIn(
+                "not implemented",
+                text.lower(),
+                f"{path.relative_to(ROOT)} still says hop is not implemented",
             )
 
     def test_docs_are_portable_diataxis(self) -> None: