feat(mcp): serve OKF bundles over MCP in two shapes, plus the generic skill

The eval was written RED at `5f1772e` with no server in the tree. This is the
capability it was written against.

`okf mcp --bundle <dir>` serves exactly one bundle, whose tools take no bundle
argument. `okf mcp --root <dir>` (repeatable) serves every bundle under the
roots and knows NONE of them by name. Four tools -- `okf_list`,
`okf_describe`, `okf_ask`, `okf_fetch` -- each carrying its reason in the
description a client actually reads.

Gate today: 1 (7/7) - 2 (83/181) - 3 (4/4) - 4 (9/9) - 5 (3/3) - 6 (6/6),
`GATE RED: rows 2`, exit 1.

THE PROTOCOL IS STDLIB, AND THAT IS THE PACKAGING INVARIANT KEPT RATHER THAN
A TASTE. An MCP SDK would be this package's second runtime dependency on the
DEFAULT install path, for four JSON-RPC methods and a newline framing, and
`test_the_only_runtime_dependency_is_the_security_boundary` pins that list
literally. Chosen hand-written because the surface needed is `initialize`,
`notifications/initialized`, `tools/list` and `tools/call`; `uv.lock` is
untouched.

NOTHING IS CACHED ACROSS CALLS, and row 3 is why. Every call re-walks the
roots and recomputes `bundle_ref`, so a bundle added, removed or rebuilt while
the process runs is seen by the next call with no restart, no configuration
edit and no code change -- 9 of 9 discovery checks over three bundles written
while the server was serving. The cost is paid per call and is published
rather than hidden: 0.75 s for the identity of a 2 756-concept bundle, 5.6 s
for one ask, 4 min 13 s for row 2's full run over four bundles.

CONTAINMENT IS TWO INDEPENDENT CHECKS: the bundle's own index must name the
concept, AND `connectors.safe_resolve` must place it inside the bundle. A
mutant removing either one alone still refuses -- with a DIFFERENT code, which
row 6 asserts by name -- and one removing both is killed. Row 6 declares a
code set per case because its first run had the 10 MB concept refused as
`concept_unknown`: the fixture had not named the file in the index, so the
size ceiling never ran and the row was green for a reason unrelated to the
attack.

`okf card <bundle>` and `okf skill --generic` are the one-to-many skill
candidate. The card is DERIVED on every run and never written into the bundle:
storing it would move the bytes of all six `examples/*/expected-bundle` trees
(23 files compared byte-for-byte) and of the pinned reference bundle, to keep
something recomputable in under a second, and a stored card is one more
artefact that can disagree with what is beside it. Measured here rather than
taken from the order: two per-bundle skills are identical on 280 of 312 and
310 lines; the 62 that differ are identity, concept count, the
conditional-field table, the whole-bundle cost and the breaking point. The
generic skill carries none of them, and `render_generic()` takes no argument,
so there is no bundle it could have read.

Row 2 decomposes into three numbers and the middle one is the finding: 99 of
181 (bundle, anchor) pairs are present in the bundles at all, 83 of those 99
were reached, and 0 of 83 were met by `okf_fetch` on the anchor as a concept
id. The set's anchors and this library's concept ids are different
vocabularies, so every pair met was met through the ranker -- 83 is a FLOOR on
the ceiling, never the ceiling.

13 mutants in a scratch copy, never in the working tree: 12 killed, 1 survived
with its mechanism printed, 0 errors, control green first. Suite 2323 passed,
2 skipped. The architecture choice between the two shapes is the OPERATOR's;
these rows are its input. Report: docs/2026-09-20-mcp-to-varianter.md.

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

src/llm_ingestion_okf/cli.py

@@ -105,7 +105,7 @@ __all__ = ["DEFAULT_STAMP", "build", "main", "measure"]
 #:
 #: Imported lazily inside the dispatch: `okf build` should not pay to import
 #: the ranker, and `okf consume` should not pay to import the proposer.
-DELEGATED = ("consume", "check", "skill", "project", "quality")
+DELEGATED = ("consume", "check", "skill", "project", "quality", "card", "mcp")
 
 
 def _delegate(command: str, argv: list[str]) -> int:
@@ -117,6 +117,10 @@ def _delegate(command: str, argv: list[str]) -> int:
         from .skill import main as run
     elif command == "quality":
         from .quality import main as run
+    elif command == "card":
+        from .skill import card_main as run
+    elif command == "mcp":
+        from .mcp_server import main as run
     else:
         from .project import main as run
     return run(argv)
@@ -648,6 +652,8 @@ def parse_args(argv: list[str] | None) -> argparse.Namespace:
         ("skill", "instantiate the consumption skill template for one bundle"),
         ("project", "folder in, bundle plus skill out: build and skill in one step"),
         ("quality", "judge one bundle per file type, with the denominator"),
+        ("card", "print one bundle's own identity, counts and denominators as JSON"),
+        ("mcp", "serve one bundle, or every bundle under a root, over MCP on stdio"),
     ):
         subcommands.add_parser(delegated, help=blurb, add_help=False)
     build_parser = subcommands.add_parser(