refactor: rename internal Fai* design system + fai_ helpers to chain

The Studio design system, widgets and helpers carried a Fai* / fai_
prefix (FaiSpace, FaiColors, FaiTheme, FaiLog, 17 fai_*.dart files, the
faiBinary* l10n keys). Studio is the Ch∆In product, so rename them to
Chain* / chain_ — carefully preserving English fail/failure/failed.
Also fix stale references: the 'fai' binary in l10n strings -> 'chain',
FAI_* env vars (FAI_BIN/DATA_DIR/MODULES_DIR/TODAY/BOOTSTRAP_TOKEN) ->
CHAIN_*, fai_platform -> fai_chain, fai_hub -> chain_hub. Vendor
security-hook tooling (FAI_BANNED_TERMS_FILE) + the .fai bundle ext left.
flutter analyze + test: clean (20 passed).

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

test/chain_log_test.dart

@@ -1,36 +1,36 @@
-// Unit tests for FaiLog — the central error log that
+// Unit tests for ChainLog — the central error log that
 // `~/.fai/logs/studio-errors.log` is the operator-visible
 // surface of. The tests redirect the singleton at a temp file
-// via `FaiLog.testPathOverride` so the real log under HOME is
+// via `ChainLog.testPathOverride` so the real log under HOME is
 // never touched.
 
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:chain_studio/data/fai_log.dart';
+import 'package:chain_studio/data/chain_log.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 void main() {
-  group('FaiLog', () {
+  group('ChainLog', () {
     late Directory tmp;
     late File logFile;
 
     setUp(() {
-      tmp = Directory.systemTemp.createTempSync('fai_log_test_');
+      tmp = Directory.systemTemp.createTempSync('chain_log_test_');
       logFile = File('${tmp.path}/studio-errors.log');
-      FaiLog.testPathOverride = logFile.path;
+      ChainLog.testPathOverride = logFile.path;
     });
 
     tearDown(() {
-      FaiLog.testPathOverride = null;
+      ChainLog.testPathOverride = null;
       try {
         tmp.deleteSync(recursive: true);
       } catch (_) {/* best-effort */}
     });
 
     test('append writes one JSON-shaped line per event', () async {
-      await FaiLog.instance.error('flows.run', 'boom');
-      final lines = await FaiLog.instance.tail();
+      await ChainLog.instance.error('flows.run', 'boom');
+      final lines = await ChainLog.instance.tail();
       expect(lines, hasLength(1));
       final entry = jsonDecode(lines.single) as Map<String, Object?>;
       expect(entry['source'], 'flows.run');
@@ -40,22 +40,22 @@ void main() {
     });
 
     test('context field is preserved when supplied', () async {
-      await FaiLog.instance.error(
+      await ChainLog.instance.error(
         'theme.plugin.load',
         Exception('endpoint unreachable'),
         context: 'capability=studio.theme.space',
       );
-      final lines = await FaiLog.instance.tail();
+      final lines = await ChainLog.instance.tail();
       final entry = jsonDecode(lines.single) as Map<String, Object?>;
       expect(entry['context'], 'capability=studio.theme.space');
       expect(entry['error'], contains('endpoint unreachable'));
     });
 
     test('tail returns oldest first', () async {
-      await FaiLog.instance.error('a', '1');
-      await FaiLog.instance.error('b', '2');
-      await FaiLog.instance.error('c', '3');
-      final lines = await FaiLog.instance.tail();
+      await ChainLog.instance.error('a', '1');
+      await ChainLog.instance.error('b', '2');
+      await ChainLog.instance.error('c', '3');
+      final lines = await ChainLog.instance.tail();
       expect(lines, hasLength(3));
       final sources = lines.map((l) => jsonDecode(l)['source']).toList();
       expect(sources, ['a', 'b', 'c']);
@@ -63,9 +63,9 @@ void main() {
 
     test('tail caps output at maxLines and keeps the newest', () async {
       for (var i = 0; i < 20; i++) {
-        await FaiLog.instance.error('burst', 'event-$i');
+        await ChainLog.instance.error('burst', 'event-$i');
       }
-      final lines = await FaiLog.instance.tail(maxLines: 5);
+      final lines = await ChainLog.instance.tail(maxLines: 5);
       expect(lines, hasLength(5));
       final last = jsonDecode(lines.last) as Map<String, Object?>;
       expect(last['error'], 'event-19');
@@ -77,7 +77,7 @@ void main() {
       // `.log.1` and a short fresh `.log`.
       logFile.parent.createSync(recursive: true);
       logFile.writeAsBytesSync(List.filled(257 * 1024, 0x20));
-      await FaiLog.instance.error('rotation', 'after-cap');
+      await ChainLog.instance.error('rotation', 'after-cap');
       expect(File('${logFile.path}.1').existsSync(), isTrue);
       final newSize = logFile.lengthSync();
       expect(newSize, lessThan(2 * 1024));
@@ -86,16 +86,16 @@ void main() {
     });
 
     test('path getter returns the override when set', () {
-      expect(FaiLog.instance.path, logFile.path);
+      expect(ChainLog.instance.path, logFile.path);
     });
 
     test('writes failing silently does not throw', () async {
       // Redirect to a deliberately impossible path. The error()
       // call must complete cleanly; the operator UI must never
       // crash because the disk is full / read-only / missing.
-      FaiLog.testPathOverride = '/this/path/does/not/exist/ever/x.log';
+      ChainLog.testPathOverride = '/this/path/does/not/exist/ever/x.log';
       await expectLater(
-        FaiLog.instance.error('bad.path', 'boom'),
+        ChainLog.instance.error('bad.path', 'boom'),
         completes,
       );
     });

test/integration/README.md

@@ -35,14 +35,14 @@ flutter test test/integration/
 ```
 
 Prereq: a `fai` binary on PATH or at
-`../fai_platform/target/release/fai`. The harness skips with a
+`../fai_chain/target/release/chain`. The harness skips with a
 clear message when neither exists, so this command does not
 fail on a fresh checkout — it just reports skipped tests.
 
 To get the binary:
 
 ```bash
-cd ../fai_platform
+cd ../fai_chain
 cargo build --release --bin fai
 ```
 
@@ -52,11 +52,11 @@ A cold `chain serve` spends its first ~30s building the
 curated-model database and initialising SQLite migrations.
 `HubFixture.start()` waits up to 60s by default; if your local
 hub takes longer the first time, run `chain serve` once by hand
-against any temp `FAI_DATA_DIR` to warm the per-user cargo /
+against any temp `CHAIN_DATA_DIR` to warm the per-user cargo /
 SBOM caches:
 
 ```bash
-FAI_DATA_DIR=/tmp/fai_warmup chain serve --bind 127.0.0.1:0
+CHAIN_DATA_DIR=/tmp/chain_warmup chain serve --bind 127.0.0.1:0
 # wait for "hub started", Ctrl-C
 ```
 
@@ -66,7 +66,7 @@ Subsequent integration-test runs are quick.
 
 `.forgejo/workflows/ci.yml` doesn't run these yet. Adding them
 needs an artifact-passing pattern: the platform build job
-publishes `target/release/fai` as a CI artifact; the studio
+publishes `target/release/chain` as a CI artifact; the studio
 test job consumes it. Pattern is straightforward once we want
 it; it's deferred because we don't yet have enough integration
 tests to justify the CI runtime.

test/integration/capabilities_test.dart

@@ -22,7 +22,7 @@
 //   flutter test test/integration/
 //
 // CI does not yet run these by default — they need a built `fai`
-// binary in PATH or in ../fai_platform/target/release/. Wire that
+// binary in PATH or in ../chain_platform/target/release/. Wire that
 // in via .forgejo/workflows/ci.yml once the platform CI publishes
 // a Linux binary as an artifact for downstream jobs to consume.
 

test/integration/hub_fixture.dart

@@ -72,7 +72,7 @@ class HubFixture {
       if (skipIfBinaryMissing) {
         markTestSkipped(
           'Hub fixture skipped: no `fai` binary found on PATH or in '
-          '../fai_platform/target/release/fai. Build it with '
+          '../chain_platform/target/release/fai. Build it with '
           '`cargo build --release` and re-run.',
         );
         return null;
@@ -86,15 +86,15 @@ class HubFixture {
 
     // Run as a child process. `serve --bind` lets us avoid the
     // default 50051 (and any local daemon the developer happens
-    // to be running). FAI_DATA_DIR keeps the temp footprint
+    // to be running). CHAIN_DATA_DIR keeps the temp footprint
     // contained — no state leaks into ~/.fai.
     final process = await Process.start(
       binary,
       ['serve', '--bind', addr],
       environment: {
         ...Platform.environment,
-        'FAI_DATA_DIR': tempDir.path,
-        'FAI_MODULES_DIR': '${tempDir.path}/modules',
+        'CHAIN_DATA_DIR': tempDir.path,
+        'CHAIN_MODULES_DIR': '${tempDir.path}/modules',
         // Suppress info logs without a CLI flag — the binary
         // respects RUST_LOG for tracing-subscriber.
         'RUST_LOG': 'warn',
@@ -136,7 +136,7 @@ class HubFixture {
     await tempDir.delete(recursive: true);
     throw StateError(
       'Hub did not become healthy within $readyTimeout. '
-      'Check `fai serve` works manually with FAI_DATA_DIR=$tempDir.',
+      'Check `fai serve` works manually with CHAIN_DATA_DIR=$tempDir.',
     );
   }
 
@@ -172,8 +172,8 @@ class HubFixture {
     }
 
     final candidate = Platform.isWindows
-        ? '../fai_platform/target/release/fai.exe'
-        : '../fai_platform/target/release/fai';
+        ? '../chain_platform/target/release/fai.exe'
+        : '../chain_platform/target/release/fai';
     final f = File(candidate);
     if (await f.exists()) {
       return f.absolute.path;

test/integration/plugin_theme_test.dart

@@ -10,9 +10,9 @@
 //   flutter test test/integration/plugin_theme_test.dart
 //
 // Pre-reqs (handled by HubFixture's skip-when-missing path):
-//   - fai binary on PATH or at ../fai_platform/target/release/fai
+//   - fai binary on PATH or at ../chain_platform/target/release/fai
 //   - studio-theme-solarized plugin built to module.wasm in its
-//     fai_plugins dir.
+//     chain_plugins dir.
 
 import 'dart:io';
 
@@ -33,7 +33,7 @@ void main() {
         // add network + bundle-fetch latency that doesn't
         // belong in an in-process round-trip test.
         final pluginSrc = Directory(
-          '../fai_plugins/studio-theme-solarized',
+          '../chain_plugins/studio-theme-solarized',
         );
         if (!await pluginSrc.exists()) {
           markTestSkipped('studio-theme-solarized source not available');

test/load_docs_test.dart

@@ -7,7 +7,7 @@ import 'package:chain_studio/l10n/app_localizations.dart';
 import 'package:chain_studio/theme/theme.dart';
 
 /// Recreates the exact DocReaderSheet code path that
-/// welcome.dart uses, including FaiTheme.markdownStyle, so a
+/// welcome.dart uses, including ChainTheme.markdownStyle, so a
 /// regression in either rootBundle, the markdown parser, or
 /// the style sheet surfaces here instead of only at runtime
 /// when an operator clicks a doc card.
@@ -16,7 +16,7 @@ void main() {
 
   testWidgets('DocReaderSheet renders all four german + english docs',
       (tester) async {
-    final theme = FaiTheme.light();
+    final theme = ChainTheme.light();
     for (final slug in ['architecture', 'security', 'audit', 'flows']) {
       for (final locale in ['de', 'en']) {
         final path = locale == 'de'
@@ -39,7 +39,7 @@ void main() {
               data: text,
               padding: const EdgeInsets.all(8),
               selectable: true,
-              styleSheet: FaiTheme.markdownStyle(theme),
+              styleSheet: ChainTheme.markdownStyle(theme),
             ),
           ),
         ));