fix(search): show the passage that matched, not the opening of the body (#4243)

Raised by the operator: are we limiting what comes back by character count,
and how do we verify the pertinent part is the part displayed?

We were not. mcp/tools/search.py sent (note.body or "")[:240] — a head cut,
with no marker that anything had been removed, so a 240-character preview of
a 4000-character record was indistinguishable from a complete short one.

The opening is the wrong span. The match is semantic and per chunk, and
semantic_search_notes collapses to best-chunk-per-note — its own comment at
the collapse says "the first appearance of a note is its best chunk". So the
system identified the passage that earned the hit and then discarded it:
select(Note, distance) kept no chunk column. A record could rank first on its
sixth paragraph, be previewed by its first, and be judged irrelevant on a
span the search had already scored lower. That biases against long records,
and it is self-concealing — the caller who does not open it never learns the
preview was misleading.

  - embeddings: chunk_index/chunk_text ride along in the select, and the
    collapse records the winner in report["best_chunk"]. Carried in `report`,
    NOT by widening the return tuple: ten callers unpack (score, note) at
    ~18 sites and nothing would catch the misses (lesson #4207). `report` is
    the side-channel this function already uses for best_available_score.
  - search(): excerpt / excerpt_is / body_length, and read_full when there is
    more. A caller that cannot tell a matched passage from a document opening
    cannot judge whether to look deeper, which is the only decision the field
    supports.

elide() moves to services/text.py so both callers share one copy, and it
keeps BOTH ends with a stated gap — it is the fallback for when nothing
identifies a better span than "all of it", not the goal.

Also fixes a guard that produced a false failure on the previous commit:
test_pull_telemetry checked `"project_id: int = 0" in body.split("\n")[0]`,
which sees only the first line, so wrapping get_task's signature over four
lines made it report a function that does take the project as one that does
not. Parsed with ast now, and proven to still reject an absent or
wrongly-typed parameter rather than being appeased by reflowing the code.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

tests/test_pull_telemetry.py

@@ -224,13 +224,34 @@ def _pulling_getters():
             yield module, name, body
 
 
+def _takes_reading_project(body: str) -> bool:
+    """Does this function declare `project_id: int = 0`?
+
+    Parsed, not string-matched against the first line. The first version read
+    `body.split("\n")[0]`, which sees only as far as the first newline — so
+    adding a parameter to `get_task` wrapped its signature over four lines and
+    the guard reported a function that DOES take the project as one that does
+    not. A guard that fails on formatting is a guard that gets appeased by
+    reflowing the code it was meant to check.
+    """
+    node = ast.parse(body).body[0]
+    args = node.args
+    params = list(args.posonlyargs) + list(args.args) + list(args.kwonlyargs)
+    for arg in params:
+        if arg.arg != "project_id":
+            continue
+        ann = getattr(arg, "annotation", None)
+        return isinstance(ann, ast.Name) and ann.id == "int"
+    return False
+
+
 def test_every_getter_that_pulls_takes_the_reading_project():
     """Asserted on structure (rule 167): a behavioural test cannot see a
     parameter that was never threaded through."""
     missing = [
         f"{module}.{name}"
         for module, name, body in _pulling_getters()
-        if "project_id: int = 0" not in body.split("\n")[0]
+        if not _takes_reading_project(body)
     ]
     assert not missing, (
         f"these getters record a pull but cannot say where the reader was: "