feat(extraction): add COBOL language support (.cbl/.cob/.cpy) (#590, #648) (#1161)

Programs, sections/paragraphs (reconstructed extents over the grammar's
flat header stream), PERFORM/THRU/GO TO/CALL call edges, COPY copybook
imports incl. standalone .cpy fragments, DATA DIVISION records/fields/
88-levels with write-site impact references, and CICS flows: EXEC
LINK/XCTL program targets (literal + same-file VALUE deref), EXEC SQL
INCLUDE, and pseudo-conversational RETURN/START TRANSID hops resolved
to the owning program via a CICS framework resolver. Fixed and free
source format (free format via a scanner wide-mode sentinel).

Grammar: vendored wasm built from a patched yutaro-sakamoto/
tree-sitter-cobol (EXEC blocks as an external-scanner token, copybook
fragment entry point, single-quote continuation, COPY REPLACING
pseudo-text, NOT=, CALL GIVING, ENTRY, FREE, bitwise ops, abbreviated
relations, COBOL-2002 usages, and more). Patch + provenance + upstream
PR draft in docs/grammars/. Parse health: AWS CardDemo 43/44 native
(upstream: 9/31), 44/44 through preParse; copybooks 28/29; CobolCraft
free-format 17/17 (upstream: 0); NIST COBOL85 unchanged at 373/382.

Copybook members resolve to files like C includes (basename index,
name-matcher short-circuit so compiler-supplied members stay honestly
unresolved): CardDemo imports 5 -> 285. Impact proof: ACCT-CURR-BAL
(CVACT01Y copybook) surfaces its 4 writer programs cross-file.

Also: run-all.sh now neutralizes the ambient prompt-hook in both A/B
arms (CODEGRAPH_NO_PROMPT_HOOK=1); COBOL corpus entries for agent-eval.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

scripts/agent-eval/run-all.sh

@@ -19,6 +19,12 @@ OUT="${AGENT_EVAL_OUT:-/tmp/agent-eval}"
 HARNESS="$(cd "$(dirname "$0")" && pwd)"
 mkdir -p "$OUT"
 
+# Neutralize any ambient CodeGraph prompt-hook (~/.claude) in BOTH arms:
+# the hook injects codegraph context into every prompt, which contaminates
+# the without-arm (free structural context) and double-counts the with-arm.
+# The A/B's only variable must be the MCP server wired below.
+export CODEGRAPH_NO_PROMPT_HOOK=1
+
 [ -n "$CG_BIN" ] || { echo "no codegraph binary on PATH (set CG_BIN)"; exit 1; }
 [ -d "$REPO/.codegraph" ] || { echo "no .codegraph index at $REPO — index it first"; exit 1; }
 case "$MODE" in headless|tmux|all) ;; *) echo "mode must be headless|tmux|all (got '$MODE')"; exit 1;; esac