feat(ledger): write-path stamping — a pulled canon the session then instantiates lands as a hook instance row (#2791, milestone 294 step 5)

The prior-art hook now names the shapes being written (shapes=kind:name —
every definition in the payload, or the one enclosing an Edit found by
walking the file upward) and the server stamps them as instance rows when
the session PULLED a snippet inside PULL_WINDOW that the payload references
by symbol or that the semantic arm scored for this very payload.
classified_by=hook, evidence in reason; never overrides a judgment or a
canonical row, overridable by classify_shapes. Offered-but-unopened stamps
nothing. Pulled-and-already-seen snippets stay in the semantic query as
evidence without re-entering the deduped menu. A brand-new shape gets a
provisional row the next sync confirms or vanishes. Read-scoped keys get
the hint, never the stamp. Plugin 0.1.34.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_shape_ledger.py

@@ -82,3 +82,56 @@ def test_classify_and_list_are_mounted_as_mcp_tools():
     mcp = build_mcp_server()
     for name in ("classify_shapes", "list_shapes", "refresh_pattern_coverage"):
         assert mcp._tool_manager.get_tool(name) is not None
+
+
+# --- step 5: the write-path feed's evidence tests (pure) ---------------------
+
+
+def test_symbol_reference_is_word_bounded_and_kind_aware():
+    from scribe.services.shape_ledger import references_symbol as ref
+
+    code = "const ok = await confirmed({ title: 'x' });\nif (!ok) return;"
+    assert ref(code, "confirmed", "sym")
+    assert not ref(code, "confirm", "sym")          # prefix never claims the call
+    assert not ref("", "confirmed", "sym")
+    assert not ref(code, "", "sym")
+    # CSS: the class as a selector or inside a class attribute; dashes are part
+    # of the name, so `btn` must not claim `btn-primary`.
+    html = '<button class="btn btn-primary">Go</button>'
+    assert ref(html, ".btn-primary", "css")
+    assert ref(html, "btn-primary", "css")
+    assert ref(".btn-primary { color: red }", ".btn-primary", "css")
+    assert not ref('<button class="btn-primary">', ".btn", "css")
+    assert ref('<button class="btn-primary btn">', ".btn", "css")
+
+
+def test_snippet_kind_reads_the_symbol_then_the_language():
+    from scribe.services.shape_ledger import snippet_kind
+
+    assert snippet_kind(".btn-primary", "css") == "css"
+    assert snippet_kind(".btn-primary", "") == "css"
+    assert snippet_kind("confirmed", "typescript") == "sym"
+    assert snippet_kind("", "scss") == "css"      # whole-stylesheet record
+    assert snippet_kind("", "python") == "sym"
+
+
+def test_route_shapes_param_parses_capped_and_deduped():
+    from scribe.routes.plugin import _SHAPES_CAP, _parse_shapes
+
+    assert _parse_shapes("css:btn-primary,sym:onTrash") == [
+        ("css", "btn-primary"), ("sym", "onTrash"),
+    ]
+    assert _parse_shapes(" sym:a , sym:a ,bogus:x,sym:,:,") == [("sym", "a")]
+    assert _parse_shapes("") == []
+    many = ",".join(f"sym:f{i}" for i in range(40))
+    assert len(_parse_shapes(many)) == _SHAPES_CAP
+
+
+def test_hook_is_a_server_internal_classifier():
+    """`hook` is in the status vocabulary but NOT a via a caller may claim —
+    a classify_shapes call saying via="hook" would launder judgment as
+    evidence (the reverse of the stamping rule's point)."""
+    from scribe.services.shape_ledger import _CALLER_VIAS
+
+    assert "hook" in SHAPE_CLASSIFIERS
+    assert "hook" not in _CALLER_VIAS