docs(fork-c/S0): setup contract — byte-baseline + commit-discipline, E6b disposition + two-corpus partition, A–E6 reuse/delete ledger

S0 of the ratified Fork C plan (zero-legacy name-resolution redesign, S0→S6).
Pure setup/documentation: NO production code change, NO behavior change.
Single-author output byte-identical to wt-stdlib-base by construction.

Deliverables under docs/fork-c/ (docs/, not current/, because current/ is
gitignored and the contract must be committed):

S0.1 — byte-baseline + commit-discipline: the committed examples/expected/*
snapshots are the single-author byte-identity reference; the zero-diff repro is
`zig build && zig build test && bash tests/run_examples.sh`. Resolver-target set
explicitly excluded + listed. Commit-classification rule: mirror | consumer-cutover | deletion.

S0.2 — E6b disposition + two-corpus partition: transitional E6b src NOT merged
(grep-clean: no resolveRegistrationSigTypeInSource / sig_registration_mode /
e6br_gate.test.zig on baseline). Harvested 0811–0829 trees + goldens (never the
src), empirically partitioned by running each through the base compiler vs the
E6b target:
  - baseline-green (mirror-equivalence): 0795–0798 (merged) + 0823, 0828 — given
    examples/expected/ markers, locked into the S0 baseline.
  - resolver-target (known-wrong old behavior): 0811–0822, 0824–0827, 0829 + the
    re-filed E6BR-5 nested-pattern regression — a listed xfail harness under
    tests/resolver-target/ (manifest + TARGET goldens, NO active marker), flips
    active+green at S3.9. 0811/0829 noted as old-selector-wrong on the E6b-unmerged
    base; E6BR-5 subsumed by the whole-AST resolver, NOT an E6b attempt-6.

S0.3 — A–E6 reuse/delete ledger: every load-bearing A–E6 artifact mapped REUSED
(Fork C home) or DELETED/TRANSITIONAL (S3/S6 phase); E6c/d/e dropped, F/H/I/K
absorbed/superseded.

Gate over the baseline-green corpus: zig build + zig build test (LSP corpus sweep
574 files, no crash) + bash tests/run_examples.sh (540 passed, 0 failed) all exit 0.

tests/resolver-target/run_resolver_target.sh

@@ -0,0 +1,89 @@
+#!/bin/bash
+# Resolver-target xfail harness (Fork C S0.2).
+#
+# NOT part of the baseline gate. The baseline gate is `zig build && zig build test
+# && bash tests/run_examples.sh` over the BASELINE-GREEN corpus only; this harness
+# is a separate, listed diagnostic so the resolver-target corpus is never silently
+# dropped between S0 and S3.9.
+#
+# Contract (S0 -> S3.8): every case below currently FAILS to match its TARGET
+# golden on wt-stdlib-base (the old selector is known-wrong for it). This script
+# runs each case and asserts the MISMATCH. It exits 0 when ALL cases still xfail
+# (as expected today), and exits 1 if any case unexpectedly MATCHES its target —
+# which means that case is actually baseline-green and must be re-classified
+# (moved to examples/expected/ with an active marker), not silently left here.
+#
+# At S3.9 the Fork C resolver makes these pass; the flip is then performed by
+# moving each golden to examples/expected/ and this harness goes empty.
+#
+# Usage: bash tests/resolver-target/run_resolver_target.sh
+
+set -uo pipefail
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+ROOT_DIR="$(cd "$SCRIPT_DIR/../.." && pwd)"
+SX="$ROOT_DIR/zig-out/bin/sx"
+EXP_DIR="$SCRIPT_DIR/expected"
+TIMEOUT=10
+
+normalize() {
+    sed -E \
+        -e 's/0x[0-9a-f]{4,}/0xADDR/g' \
+        -e 's#(/[^[:space:]]*)?/(examples|issues)/#\2/#g'
+}
+
+if [[ ! -x "$SX" ]]; then
+    echo "error: $SX not built — run 'zig build' first" >&2
+    exit 2
+fi
+
+TMP_ERR="$(mktemp)"
+trap 'rm -f "$TMP_ERR"' EXIT
+
+XFAIL=0      # currently-failing as expected
+LEAKED=0     # unexpectedly matches target -> must be reclassified baseline-green
+MISSING=0
+
+for exit_file in "$EXP_DIR"/*.exit; do
+    [[ -e "$exit_file" ]] || continue
+    name=$(basename "$exit_file" .exit)
+
+    # Source tree: harvested 08xx live under examples/; e6br5 under cases/.
+    if [[ -f "$ROOT_DIR/examples/${name}.sx" ]]; then
+        sx_file="$ROOT_DIR/examples/${name}.sx"
+    elif [[ -f "$SCRIPT_DIR/cases/${name}.sx" ]]; then
+        sx_file="$SCRIPT_DIR/cases/${name}.sx"
+    else
+        printf '  %-55s MISSING-SOURCE\n' "$name"
+        MISSING=$((MISSING + 1))
+        continue
+    fi
+
+    actual_out=$(timeout "$TIMEOUT" "$SX" run "$sx_file" 2>"$TMP_ERR" | normalize)
+    actual_exit=${PIPESTATUS[0]}
+    actual_err=$(normalize < "$TMP_ERR")
+
+    target_exit=$(cat "$exit_file")
+    # spec-only targets (e6br5) have no .stdout/.stderr — compare exit only.
+    if [[ -f "$EXP_DIR/${name}.stdout" ]]; then
+        target_out=$(normalize < "$EXP_DIR/${name}.stdout")
+        target_err=$(normalize < "$EXP_DIR/${name}.stderr")
+        if [[ "$actual_exit" == "$target_exit" && "$actual_out" == "$target_out" && "$actual_err" == "$target_err" ]]; then
+            matches=1
+        else
+            matches=0
+        fi
+    else
+        [[ "$actual_exit" == "$target_exit" ]] && matches=1 || matches=0
+    fi
+
+    if [[ $matches -eq 1 ]]; then
+        printf '  %-55s LEAKED (matches target on base -> reclassify baseline-green)\n' "$name"
+        LEAKED=$((LEAKED + 1))
+    else
+        printf '  %-55s xfail (base exit=%s, target exit=%s)\n' "$name" "$actual_exit" "$target_exit"
+        XFAIL=$((XFAIL + 1))
+    fi
+done
+
+echo "$XFAIL xfail (expected), $LEAKED leaked, $MISSING missing-source"
+[[ $LEAKED -eq 0 && $MISSING -eq 0 ]]