Add current-draft diagnostic underlines and passive hover

Preserve raw include diagnostic provenance and derive bands from the existing shaped editor. Retain deferred tooltip paragraphs through rendering. Include source, regression, failure and native-trial evidence; corrected native acceptance remains pending.

harness/experiments/text-diagnostics-20260913/probe/run_probe.py

@@ -0,0 +1,32 @@
+from pathlib import Path
+import datetime, hashlib, json, os, subprocess, sys, time
+
+base = Path(__file__).resolve().parent
+record = base / 'records' / sys.argv[1]
+record.mkdir(parents=True, exist_ok=False)
+def now(): return datetime.datetime.now(datetime.timezone.utc).isoformat()
+def digest(path):
+    data = path.read_bytes()
+    return {'bytes': len(data), 'sha256': hashlib.sha256(data).hexdigest()}
+def inputs():
+    return {p.relative_to(base).as_posix(): digest(p) for p in sorted(base.rglob('*'))
+            if p.is_file() and p.relative_to(base).parts[0] not in ('records', 'target')}
+before = inputs()
+(record / 'inputs.json').write_text(json.dumps(before, indent=2), encoding='utf-8')
+cmd = ['cargo', 'run', '--locked', '--offline', '--manifest-path', str(base / 'Cargo.toml')]
+report = {'start': now(), 'command': cmd, 'cwd': str(base), 'inputs': digest(record / 'inputs.json'),
+          'environment': {k: os.environ.get(k) for k in ('RUSTUP_TOOLCHAIN', 'RUSTUP_HOME', 'CARGO_HOME', 'CARGO_TARGET_DIR', 'CARGO_BUILD_JOBS', 'CARGO_TARGET_X86_64_PC_WINDOWS_GNULLVM_LINKER')},
+          'cargo': subprocess.check_output(['cargo', '--version'], text=True).strip(),
+          'rustc': subprocess.check_output(['rustc', '--version'], text=True).strip()}
+(record / 'started.json').write_text(json.dumps(report, indent=2), encoding='utf-8')
+t = time.perf_counter()
+with (record / 'stdout.log').open('xb') as stdout, (record / 'stderr.log').open('xb') as stderr:
+    result = subprocess.run(cmd, cwd=base, stdout=stdout, stderr=stderr)
+report.update(finish=now(), seconds=time.perf_counter()-t, exitCode=result.returncode,
+              stdout=digest(record/'stdout.log'), stderr=digest(record/'stderr.log'), inputsUnchanged=before == inputs())
+report['passLine'] = [line for line in (record/'stdout.log').read_text(encoding='utf-8').splitlines() if line.startswith('PASS ')]
+exe = Path(os.environ['CARGO_TARGET_DIR']) / 'debug' / 'text-diagnostics-geometry-probe.exe'
+if exe.exists(): report['binary'] = {'path': str(exe), **digest(exe)}
+(record / 'result.json').write_text(json.dumps(report, indent=2), encoding='utf-8')
+print(json.dumps(report, indent=2))
+sys.exit(0 if result.returncode == 0 and report['inputsUnchanged'] and len(report['passLine']) == 1 else 1)