Unlucky Launcher v0.2.0

首个 iced + Material 3 Expressive 版本的源码快照。
完整历史与日常提交在 dev 分支；main 只放阶段性快照。

crates/core/tests/download/backoff_test.rs

@@ -0,0 +1,68 @@
+//! 指数退避与抖动的单测（纯函数，无网络）。
+
+use std::time::Duration;
+
+use unlucky_core::download::backoff::{BackoffPolicy, Jitter};
+
+#[test]
+fn exponential_growth_doubles_and_caps() {
+    let policy = BackoffPolicy::default();
+    assert_eq!(policy.delay(0), Duration::from_millis(1_000));
+    assert_eq!(policy.delay(1), Duration::from_millis(2_000));
+    assert_eq!(policy.delay(2), Duration::from_millis(4_000));
+    assert_eq!(policy.delay(3), Duration::from_millis(8_000));
+    // 上限封顶，不会涨到分钟级。
+    assert_eq!(policy.delay(10), Duration::from_millis(30_000));
+    assert_eq!(policy.delay(u32::MAX), Duration::from_millis(30_000));
+}
+
+#[test]
+fn no_retry_policy_waits_nothing() {
+    let policy = BackoffPolicy::none();
+    assert_eq!(policy.delay(0), Duration::ZERO);
+    assert_eq!(policy.max_attempts, 1);
+    assert_eq!(policy.delay_jittered(0, 0.5), Duration::ZERO);
+}
+
+#[test]
+fn jitter_stays_within_ratio_bounds() {
+    let policy = BackoffPolicy::default();
+    // base 1000ms ± 30% → [700, 1300]
+    let low = policy.delay_jittered(0, 0.0);
+    let high = policy.delay_jittered(0, 1.0);
+    assert_eq!(low, Duration::from_millis(700));
+    assert_eq!(high, Duration::from_millis(1_300));
+    // 抖动永不超过 max_ms。
+    for rng in [0.0, 0.25, 0.5, 0.75, 1.0] {
+        assert!(policy.delay_jittered(9, rng) <= Duration::from_millis(30_000));
+    }
+}
+
+#[test]
+fn jitter_without_ratio_is_deterministic() {
+    let policy = BackoffPolicy {
+        jitter_ratio: 0.0,
+        ..BackoffPolicy::default()
+    };
+    assert_eq!(
+        policy.delay_jittered(2, 0.0),
+        policy.delay_jittered(2, 0.99)
+    );
+}
+
+#[test]
+fn jitter_source_is_reproducible_and_in_range() {
+    let mut first = Jitter::new(42);
+    let mut second = Jitter::new(42);
+    for _ in 0..32 {
+        let a = first.next_fraction();
+        let b = second.next_fraction();
+        assert_eq!(a, b, "同种子的抖动序列必须一致");
+        assert!((0.0..1.0).contains(&a));
+    }
+
+    let mut other = Jitter::new(7);
+    assert_ne!(Jitter::new(1).next_u64(), other.next_u64());
+    // 种子 0 会被替换成固定非零种子，但仍然可用。
+    assert!((0.0..1.0).contains(&Jitter::new(0).next_fraction()));
+}

crates/core/tests/download/cache_test.rs

@@ -0,0 +1,149 @@
+//! 内容寻址缓存的单测：两级分片、记录信任（命中不重算）、损坏检测、索引持久化。
+
+mod support;
+
+use std::time::Duration;
+
+use unlucky_core::download::cache::ContentCache;
+use unlucky_core::download::types::{HashAlgo, Integrity};
+
+const NOW: u64 = 5_000_000;
+
+fn cache_dir(tag: &str) -> std::path::PathBuf {
+    support::temp_dir(tag)
+}
+
+#[test]
+fn sharded_path_follows_layout() {
+    let dir = cache_dir("cache-path");
+    let cache = ContentCache::open(&dir);
+    let integrity = Integrity::sha1("abcdef0123456789abcdef0123456789abcdef01");
+    let path = cache.path_for(integrity.algo, &integrity.hex);
+    assert!(path.ends_with("sha1/ab/abcdef0123456789abcdef0123456789abcdef01"));
+    assert!(path.starts_with(cache.root()));
+    // SHA-256 单独一棵子树。
+    let sha256_path = cache.path_for(HashAlgo::Sha256, "00112233445566778899aabbccddeeff");
+    assert!(sha256_path.ends_with("sha256/00/00112233445566778899aabbccddeeff"));
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn insert_then_lookup_hits_without_rehashing() {
+    let dir = cache_dir("cache-hit");
+    let cache = ContentCache::open(&dir);
+
+    let payload = b"hello unlucky launcher".to_vec();
+    let integrity = Integrity::sha1(support::sha1_hex(&payload));
+    let source = dir.join("download.bin");
+    std::fs::write(&source, &payload).unwrap();
+
+    let cached = cache
+        .insert(&source, &integrity, NOW)
+        .expect("写入缓存失败");
+    assert!(cached.is_file());
+    assert_eq!(cache.len(), 1);
+
+    // 第二次命中：size/mtime 未变 → 记录信任，直接返回（不重算摘要）。
+    let hit = cache.lookup(&integrity, NOW + 10).expect("应命中缓存");
+    assert_eq!(hit, cached);
+
+    // 文件被删 → 记录作废。
+    std::fs::remove_file(&cached).unwrap();
+    assert!(cache.lookup(&integrity, NOW + 20).is_none());
+    assert_eq!(cache.len(), 0);
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn truncated_cache_file_is_a_miss() {
+    let dir = cache_dir("cache-truncate");
+    let cache = ContentCache::open(&dir);
+
+    let payload = vec![7_u8; 256];
+    let integrity = Integrity::sha1(support::sha1_hex(&payload));
+    let source = dir.join("payload.bin");
+    std::fs::write(&source, &payload).unwrap();
+    let cached = cache.insert(&source, &integrity, NOW).unwrap();
+
+    // 半损坏（长度变了）必须立刻视为未命中。
+    std::fs::write(&cached, &payload[..128]).unwrap();
+    assert!(cache.lookup(&integrity, NOW + 1).is_none());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn metadata_change_forces_a_rehash() {
+    let dir = cache_dir("cache-rehash");
+    let cache = ContentCache::open(&dir);
+
+    let payload = vec![3_u8; 128];
+    let integrity = Integrity::sha1(support::sha1_hex(&payload));
+    let source = dir.join("data.bin");
+    std::fs::write(&source, &payload).unwrap();
+    let cached = cache.insert(&source, &integrity, NOW).unwrap();
+    // 硬链接/复制都可能让源文件与缓存同 inode，先断开再改缓存内容。
+    let _ = std::fs::remove_file(&source);
+
+    // 等 mtime 变化（部分文件系统时间戳精度 10ms）。
+    std::thread::sleep(Duration::from_millis(30));
+    let mut tampered = payload.clone();
+    tampered[0] = 9;
+    std::fs::write(&cached, &tampered).unwrap();
+
+    // 内容变了 → 摘要不符 → 记录作废。
+    assert!(cache.lookup(&integrity, NOW + 100).is_none());
+    assert_eq!(cache.len(), 0);
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn lookup_verified_rejects_wrong_content_with_same_size() {
+    let dir = cache_dir("cache-verified");
+    let cache = ContentCache::open(&dir);
+
+    let payload = vec![1_u8; 64];
+    let integrity = Integrity::sha1(support::sha1_hex(&payload));
+    // 直接放到缓存位但内容是错的（模拟外部篡改 / 镜像写坏）。
+    let path = cache.path_for(integrity.algo, &integrity.hex);
+    std::fs::create_dir_all(path.parent().unwrap()).unwrap();
+    std::fs::write(&path, vec![2_u8; 64]).unwrap();
+    cache.register(&path, &integrity, NOW).unwrap();
+
+    assert!(
+        cache.lookup_verified(&integrity, NOW + 1).is_none(),
+        "强制校验必须发现内容不符"
+    );
+
+    // 内容对了就能通过。
+    std::fs::write(&path, &payload).unwrap();
+    cache.register(&path, &integrity, NOW).unwrap();
+    assert!(cache.lookup_verified(&integrity, NOW + 2).is_some());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn index_persists_across_reopen() {
+    let dir = cache_dir("cache-persist");
+    let payload = vec![5_u8; 32];
+    let integrity = Integrity::sha1(support::sha1_hex(&payload));
+
+    {
+        let cache = ContentCache::open(&dir);
+        let source = dir.join("src.bin");
+        std::fs::write(&source, &payload).unwrap();
+        cache.insert(&source, &integrity, NOW).unwrap();
+        cache.persist().expect("持久化索引失败");
+        assert_eq!(cache.stats().entries, 1);
+        assert_eq!(cache.stats().total_bytes, 32);
+    }
+
+    let reopened = ContentCache::open(&dir);
+    assert_eq!(reopened.len(), 1);
+    assert!(reopened.lookup(&integrity, NOW + 1).is_some());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/core/tests/download/chunked_test.rs

@@ -0,0 +1,375 @@
+//! 分块规划与 Range 语义的单测（纯函数）+ 真跑 4 连接的端到端用例（mock 源）。
+
+mod support;
+
+use std::sync::Arc;
+use std::time::Duration;
+
+use unlucky_core::download::backoff::BackoffPolicy;
+use unlucky_core::download::cache::ContentCache;
+use unlucky_core::download::chunked::{
+    content_range_matches, parse_content_range, plan, range_support, ByteRange, ChunkedConfig,
+    ContentRange, RangeSupport, MAX_CONNECTIONS,
+};
+use unlucky_core::download::config::EngineConfig;
+use unlucky_core::download::engine::DownloadEngine;
+use unlucky_core::download::health::HealthRegistry;
+use unlucky_core::download::mirrors::MirrorTable;
+use unlucky_core::download::region::RegionProfile;
+use unlucky_core::download::types::{DownloadRequest, ResourceKind};
+
+use support::{sha1_hex, temp_dir, MockResponse, MockServer};
+
+#[test]
+fn plan_partitions_whole_file_without_gaps() {
+    let cases = [
+        (1_u64, 4_usize),
+        (3, 4),
+        (100, 4),
+        (1000, 7),
+        (123_456_789, 4),
+    ];
+    for (total, connections) in cases {
+        let ranges = plan(total, connections);
+        assert!(!ranges.is_empty(), "total={total} 不能切出空集");
+        assert_eq!(ranges[0].start, 0, "必须从 0 开始");
+        assert_eq!(ranges.last().unwrap().end, total - 1, "必须覆盖到末尾");
+        let mut next = 0_u64;
+        for range in &ranges {
+            assert_eq!(range.start, next, "段之间不能有空洞或重叠");
+            assert!(!range.is_empty());
+            next = range.end + 1;
+        }
+        assert_eq!(next, total);
+        assert_eq!(ranges.iter().map(ByteRange::len).sum::<u64>(), total);
+    }
+}
+
+#[test]
+fn plan_caps_connections_and_handles_edge_cases() {
+    assert!(plan(0, 4).is_empty());
+    // 文件比连接数还小：每段 1 字节。
+    let tiny = plan(3, 4);
+    assert_eq!(tiny.len(), 3);
+    assert!(tiny.iter().all(|range| range.len() == 1));
+    // 连接数被夹到上限。
+    let many = plan(1_000_000, 100);
+    assert_eq!(many.len(), MAX_CONNECTIONS);
+    // 单连接。
+    assert_eq!(plan(120, 1), vec![ByteRange::new(0, 119)]);
+}
+
+#[test]
+fn byte_range_headers_are_closed_intervals() {
+    let range = ByteRange::new(100, 199);
+    assert_eq!(range.len(), 100);
+    assert_eq!(range.header_value(), "bytes=100-199");
+    assert!(ByteRange::new(10, 9).is_empty());
+    assert_eq!(ByteRange::new(10, 9).len(), 0);
+}
+
+#[test]
+fn parse_content_range_accepts_servers_forms() {
+    assert_eq!(
+        parse_content_range("bytes 0-99/1000"),
+        Some(ContentRange {
+            start: 0,
+            end: 99,
+            total: Some(1000)
+        })
+    );
+    assert_eq!(
+        parse_content_range("  bytes 100-199/*  "),
+        Some(ContentRange {
+            start: 100,
+            end: 199,
+            total: None
+        })
+    );
+    // 畸形一律 None：调用方据此退化。
+    assert_eq!(parse_content_range("bytes 100-99/1000"), None);
+    assert_eq!(parse_content_range("items 0-9/10"), None);
+    assert_eq!(parse_content_range("bytes 0-9"), None);
+    assert_eq!(parse_content_range(""), None);
+}
+
+#[test]
+fn range_support_matrix() {
+    assert_eq!(range_support(Some("bytes"), 200), RangeSupport::Supported);
+    assert_eq!(range_support(None, 206), RangeSupport::Supported);
+    assert_eq!(range_support(Some("none"), 200), RangeSupport::Unsupported);
+    assert_eq!(
+        range_support(Some("crumbs"), 200),
+        RangeSupport::Unsupported
+    );
+    assert_eq!(range_support(None, 200), RangeSupport::Unknown);
+}
+
+#[test]
+fn chunked_config_gate() {
+    let config = ChunkedConfig::default();
+    assert!(config.enabled);
+    assert_eq!(config.connections, 4);
+    // 只有大文件 + 大资源类型才分块。
+    assert!(config.applies_to(ResourceKind::JavaRuntime, Some(200 * 1024 * 1024)));
+    assert!(!config.applies_to(ResourceKind::JavaRuntime, Some(1024)));
+    assert!(!config.applies_to(ResourceKind::ClientJar, Some(200 * 1024 * 1024)));
+    assert!(!config.applies_to(ResourceKind::JavaRuntime, None));
+    // 设置项关掉后一律不分块。
+    assert!(!ChunkedConfig::disabled().applies_to(ResourceKind::JavaRuntime, Some(u64::MAX)));
+    assert_eq!(
+        ChunkedConfig {
+            connections: 999,
+            ..ChunkedConfig::default()
+        }
+        .effective_connections(),
+        MAX_CONNECTIONS
+    );
+}
+
+/// 端到端：`min_size` 调到 1KiB 后，20KiB 的 JDK 类资源真的被切成 4 段并行取。
+///
+/// 断言三件事：①mock 源收到 4 次带 `Range` 的请求（不是 1 次）②拼装后的文件逐字节正确
+/// ③流式 sha1 校验通过（证明分块乱序写没有错位）。
+#[tokio::test]
+async fn downloads_large_file_over_four_parallel_ranges() {
+    let payload: Vec<u8> = (0..20 * 1024).map(|index| (index % 251) as u8).collect();
+    let server = MockServer::start(vec![
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+    ])
+    .await;
+    let url = server.url("/jdk.zip");
+    let dir = temp_dir("chunked-e2e");
+    let engine = DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: 1,
+            backoff: BackoffPolicy {
+                base_ms: 1,
+                max_ms: 2,
+                jitter_ratio: 0.0,
+                max_attempts: 1,
+            },
+            read_timeout: Duration::from_secs(5),
+            connect_timeout: Duration::from_secs(5),
+            // 真开分块：4 条连接，1KiB 以上就切。
+            chunked: ChunkedConfig {
+                enabled: true,
+                connections: 4,
+                min_size: 1024,
+            },
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::new(HealthRegistry::in_memory()),
+        Arc::new(ContentCache::open(dir.join("cache"))),
+    );
+
+    let dest = dir.join("jdk.zip");
+    let outcome = engine
+        .download(
+            DownloadRequest::new(ResourceKind::JavaRuntime, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("分块下载失败");
+
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert_eq!(outcome.source, "official");
+    assert_eq!(
+        server.hits(),
+        4,
+        "4 条连接应各发一次带 Range 的请求（退化单连接会只有 1 次）"
+    );
+    assert_eq!(std::fs::read(&dest).expect("读回落盘文件失败"), payload);
+    assert!(
+        support::part_files(&dir).is_empty(),
+        "中间文件必须在提交后消失：{:?}",
+        support::part_files(&dir)
+    );
+    server.stop();
+}
+
+/// 端到端：目标目录**还不存在**时分块下载也要能落盘。
+///
+/// 回归用例。分块路径先 `OpenOptions` 预分配整文件（不走 `PartFile::open_append`
+/// 那层建目录），所以「下到新建目录」曾让所有候选源瞬间全部失败
+/// （现场：`data/java-managed/.cache/` 未创建时装 JDK 六个源全挂）。
+#[tokio::test]
+async fn chunked_download_creates_the_destination_directory() {
+    let payload: Vec<u8> = (0..8 * 1024).map(|index| (index % 31) as u8).collect();
+    let responses = vec![
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+    ];
+    let server = MockServer::start(responses).await;
+    let url = server.url("/jdk.zip");
+    let dir = temp_dir("chunked-mkdir");
+    let engine = DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: 1,
+            backoff: BackoffPolicy {
+                base_ms: 1,
+                max_ms: 2,
+                jitter_ratio: 0.0,
+                max_attempts: 1,
+            },
+            read_timeout: Duration::from_secs(5),
+            connect_timeout: Duration::from_secs(5),
+            chunked: ChunkedConfig {
+                enabled: true,
+                connections: 4,
+                min_size: 1024,
+            },
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::new(HealthRegistry::in_memory()),
+        Arc::new(ContentCache::open(dir.join("cache"))),
+    );
+
+    let dest = dir.join("java-managed/.cache/jdk.zip");
+    assert!(
+        !dest.parent().expect("父目录").exists(),
+        "前置条件：目录不存在"
+    );
+    let outcome = engine
+        .download(
+            DownloadRequest::new(ResourceKind::JavaRuntime, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("分块下载应成功");
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert_eq!(std::fs::read(&dest).expect("读回落盘文件失败"), payload);
+    server.stop();
+}
+
+/// 端到端：服务器声明支持 Range 但实际无视（返回 200）→ 自动退化单连接，结果仍然正确。
+#[tokio::test]
+async fn falls_back_to_single_connection_when_server_ignores_range() {
+    let payload: Vec<u8> = (0..8 * 1024).map(|index| (index % 97) as u8).collect();
+    // 每个请求都会拿到 200 + 整份内容（range_support = false）。
+    // 响应条数给足：4 个分块请求可能都发出去才被 abort，退化后的整份请求是第 5 条。
+    let no_range = || MockResponse::ok(payload.clone()).without_range();
+    let server = MockServer::start(vec![
+        no_range(),
+        no_range(),
+        no_range(),
+        no_range(),
+        no_range(),
+        no_range(),
+    ])
+    .await;
+    let url = server.url("/client.jar");
+    let dir = temp_dir("chunked-fallback");
+    let engine = DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: 1,
+            backoff: BackoffPolicy::none(),
+            chunked: ChunkedConfig {
+                enabled: true,
+                connections: 4,
+                min_size: 1024,
+            },
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::new(HealthRegistry::in_memory()),
+        Arc::new(ContentCache::open(dir.join("cache"))),
+    );
+
+    let dest = dir.join("client.jar");
+    let outcome = engine
+        .download(
+            DownloadRequest::new(ResourceKind::JavaRuntime, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("退化后应仍能下载成功");
+
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert_eq!(std::fs::read(&dest).expect("读回落盘文件失败"), payload);
+    server.stop();
+}
+
+#[test]
+fn content_range_must_match_requested_segment() {
+    let requested = ByteRange::new(5120, 10239);
+    // 严格一致才放行。
+    assert!(content_range_matches(
+        requested,
+        Some("bytes 5120-10239/20480")
+    ));
+    // 起止任一不符 → 判失败（否则「长度恰好但位置错」的响应会拼出坏文件）。
+    assert!(!content_range_matches(
+        requested,
+        Some("bytes 0-5119/20480")
+    ));
+    assert!(!content_range_matches(
+        requested,
+        Some("bytes 5120-20479/20480")
+    ));
+    // 畸形头判失败。
+    assert!(!content_range_matches(requested, Some("garbage")));
+    // 缺头从宽（长度校验仍兜底）。
+    assert!(content_range_matches(requested, None));
+}
+
+/// 端到端：服务器回 206 但 `Content-Range` 谎报段位置 → 分块路径判不符、丢弃中间文件、
+/// 退化单连接重下，最终文件仍逐字节正确（不会交付拼错的文件）。
+#[tokio::test]
+async fn rejects_lying_content_range_and_falls_back() {
+    let payload: Vec<u8> = (0..8 * 1024).map(|index| (index % 89) as u8).collect();
+    let lying = || MockResponse::ok(payload.clone()).with_wrong_content_range();
+    let server = MockServer::start(vec![
+        lying(),
+        lying(),
+        lying(),
+        lying(),
+        MockResponse::ok(payload.clone()),
+    ])
+    .await;
+    let url = server.url("/jdk.zip");
+    let dir = temp_dir("chunked-lying-range");
+    let engine = DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: 1,
+            backoff: BackoffPolicy::none(),
+            chunked: ChunkedConfig {
+                enabled: true,
+                connections: 4,
+                min_size: 1024,
+            },
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::new(HealthRegistry::in_memory()),
+        Arc::new(ContentCache::open(dir.join("cache"))),
+    );
+
+    let dest = dir.join("jdk.zip");
+    let outcome = engine
+        .download(
+            DownloadRequest::new(ResourceKind::JavaRuntime, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("谎报 Content-Range 后应退化单连接成功");
+
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert_eq!(std::fs::read(&dest).expect("读回落盘文件失败"), payload);
+    server.stop();
+}

crates/core/tests/download/engine_mock_test.rs

@@ -0,0 +1,350 @@
+//! 引擎端到端（mock 源）：成功 / 退避重试 / 换源 / 校验失败 / 缓存命中 / 断点续传。
+//!
+//! 用 `tests/download/support` 里的进程内 HTTP 服务器，不发真实网络请求。
+
+mod support;
+
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::Duration;
+
+use unlucky_core::download::backoff::BackoffPolicy;
+use unlucky_core::download::cache::ContentCache;
+use unlucky_core::download::chunked::ChunkedConfig;
+use unlucky_core::download::config::EngineConfig;
+use unlucky_core::download::engine::DownloadEngine;
+use unlucky_core::download::error::DownloadErrorKind;
+use unlucky_core::download::health::HealthRegistry;
+use unlucky_core::download::mirrors::{MirrorTable, PrefixRule};
+use unlucky_core::download::progress::{ProgressEmitter, ProgressEvent};
+use unlucky_core::download::region::RegionProfile;
+use unlucky_core::download::resume::ResumeMeta;
+use unlucky_core::download::types::{DownloadRequest, HashAlgo, ResourceKind};
+
+use support::{sha1_hex, temp_dir, MockResponse, MockServer};
+
+fn fast_config(attempts: u32) -> EngineConfig {
+    EngineConfig {
+        max_attempts_per_source: attempts,
+        backoff: BackoffPolicy {
+            base_ms: 1,
+            max_ms: 2,
+            jitter_ratio: 0.0,
+            max_attempts: attempts,
+        },
+        connect_timeout: Duration::from_secs(5),
+        read_timeout: Duration::from_secs(5),
+        chunked: ChunkedConfig::disabled(),
+        ..EngineConfig::default()
+    }
+}
+
+struct Harness {
+    engine: DownloadEngine,
+    dir: PathBuf,
+}
+
+fn harness(cfg: EngineConfig, table: MirrorTable, region: RegionProfile, tag: &str) -> Harness {
+    let dir = temp_dir(tag);
+    let cache = Arc::new(ContentCache::open(dir.join("cache")));
+    let health = Arc::new(HealthRegistry::in_memory());
+    let engine = DownloadEngine::new(cfg, Arc::new(table), Arc::new(region), health, cache);
+    Harness { engine, dir }
+}
+
+fn direct_region() -> RegionProfile {
+    RegionProfile::direct(0)
+}
+
+#[tokio::test]
+async fn downloads_verifies_and_leaves_no_part_file() {
+    let payload = b"unlucky launcher payload".to_vec();
+    let server = MockServer::start(vec![MockResponse::ok(payload.clone())]).await;
+    let url = server.url("/client.jar");
+    let harness = harness(
+        fast_config(2),
+        MirrorTable::builtin(),
+        direct_region(),
+        "engine-ok",
+    );
+    let dest = harness.dir.join("versions/1.20.1/client.jar");
+
+    let request = DownloadRequest::new(ResourceKind::ClientJar, url.as_str(), &dest)
+        .with_sha1(sha1_hex(&payload))
+        .with_size(payload.len() as u64);
+    let outcome = harness.engine.download(request).await.expect("下载应成功");
+
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert!(!outcome.from_cache);
+    assert_eq!(outcome.resumed_from, 0);
+    assert_eq!(std::fs::read(&dest).unwrap(), payload);
+    let version_dir = harness.dir.join("versions/1.20.1");
+    assert!(
+        support::part_files(&version_dir).is_empty(),
+        "中间文件必须被提交掉：{:?}",
+        support::part_files(&version_dir)
+    );
+    server.stop();
+}
+
+#[tokio::test]
+async fn retries_same_source_after_server_error() {
+    let payload = b"retry me".to_vec();
+    let server = MockServer::start(vec![
+        MockResponse::status(503),
+        MockResponse::ok(payload.clone()),
+    ])
+    .await;
+    let url = server.url("/lib.jar");
+    let harness = harness(
+        fast_config(3),
+        MirrorTable::builtin(),
+        direct_region(),
+        "engine-retry",
+    );
+    let dest = harness.dir.join("lib.jar");
+
+    let outcome = harness
+        .engine
+        .download(
+            DownloadRequest::new(ResourceKind::Library, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload)),
+        )
+        .await
+        .expect("退避后应成功");
+    assert_eq!(outcome.bytes, payload.len() as u64);
+    assert_eq!(server.hits(), 2, "第一次 503 之后应重试一次");
+    server.stop();
+}
+
+#[tokio::test]
+async fn switches_to_official_when_mirror_keeps_failing() {
+    let payload = b"official wins".to_vec();
+    let official = MockServer::start(vec![MockResponse::ok(payload.clone())]).await;
+    let mirror = MockServer::start(vec![
+        MockResponse::status(500),
+        MockResponse::status(500),
+        MockResponse::status(500),
+    ])
+    .await;
+
+    let mut table = MirrorTable::builtin();
+    let official_prefix = format!("http://127.0.0.1:{}", official.port());
+    let mirror_prefix = format!("http://localhost:{}", mirror.port());
+    table.add_custom_rule(PrefixRule::new(
+        "mock-mirror",
+        official_prefix,
+        mirror_prefix,
+    ));
+
+    let harness = harness(
+        fast_config(2),
+        table,
+        RegionProfile::mirror_first(0),
+        "engine-switch",
+    );
+    let dest = harness.dir.join("client.jar");
+    let url = official.url("/client.jar");
+
+    let outcome = harness
+        .engine
+        .download(
+            DownloadRequest::new(ResourceKind::ClientJar, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload)),
+        )
+        .await
+        .expect("镜像全挂后应切到官方");
+    assert_eq!(outcome.source, "official");
+    assert_eq!(std::fs::read(&dest).unwrap(), payload);
+    assert_eq!(mirror.hits(), 2, "每个源最多尝试 max_attempts 次");
+    official.stop();
+    mirror.stop();
+}
+
+#[tokio::test]
+async fn rejects_wrong_checksum_and_falls_back() {
+    let payload = b"the real jar".to_vec();
+    let official = MockServer::start(vec![MockResponse::ok(payload.clone())]).await;
+    let mirror = MockServer::start(vec![MockResponse::ok(b"tampered by mirror".to_vec())]).await;
+
+    let mut table = MirrorTable::builtin();
+    table.add_custom_rule(PrefixRule::new(
+        "mock-mirror",
+        format!("http://127.0.0.1:{}", official.port()),
+        format!("http://localhost:{}", mirror.port()),
+    ));
+
+    let harness = harness(
+        fast_config(1),
+        table,
+        RegionProfile::mirror_first(0),
+        "engine-checksum",
+    );
+    let dest = harness.dir.join("client.jar");
+    let url = official.url("/client.jar");
+
+    let outcome = harness
+        .engine
+        .download(
+            DownloadRequest::new(ResourceKind::ClientJar, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("校验失败应换源而不是交付坏文件");
+    assert_eq!(outcome.source, "official");
+    assert_eq!(std::fs::read(&dest).unwrap(), payload);
+    assert!(mirror.hits() >= 1);
+    official.stop();
+    mirror.stop();
+}
+
+#[tokio::test]
+async fn second_download_hits_content_cache_without_network() {
+    let payload = b"cached payload".to_vec();
+    let server = MockServer::start(vec![
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+    ])
+    .await;
+    let url = server.url("/lib.jar");
+    let harness = harness(
+        fast_config(2),
+        MirrorTable::builtin(),
+        direct_region(),
+        "engine-cache",
+    );
+    let integrity = sha1_hex(&payload);
+
+    let first = harness
+        .engine
+        .download(
+            DownloadRequest::new(
+                ResourceKind::Library,
+                url.as_str(),
+                harness.dir.join("a/lib.jar"),
+            )
+            .with_sha1(integrity.as_str()),
+        )
+        .await
+        .expect("首次下载失败");
+    assert!(!first.from_cache);
+
+    let hits_after_first = server.hits();
+    let second = harness
+        .engine
+        .download(
+            DownloadRequest::new(
+                ResourceKind::Library,
+                url.as_str(),
+                harness.dir.join("b/lib.jar"),
+            )
+            .with_sha1(integrity.as_str()),
+        )
+        .await
+        .expect("缓存命中失败");
+    assert!(second.from_cache);
+    assert_eq!(second.bytes, payload.len() as u64);
+    assert_eq!(server.hits(), hits_after_first, "缓存命中不能再发请求");
+    assert_eq!(
+        std::fs::read(harness.dir.join("b/lib.jar")).unwrap(),
+        payload
+    );
+    server.stop();
+}
+
+#[tokio::test]
+async fn resumes_from_existing_part_file() {
+    let payload = b"0123456789abcdefghij".to_vec();
+    let split = 8_usize;
+    let server = MockServer::start(vec![MockResponse::ok(payload.clone())]).await;
+    let url = server.url("/client.jar");
+    let harness = harness(
+        fast_config(2),
+        MirrorTable::builtin(),
+        direct_region(),
+        "engine-resume",
+    );
+    let dest = harness.dir.join("client.jar");
+    let part = harness.dir.join("client.jar.ullpart");
+    let meta_path = harness.dir.join("client.jar.ullpart.ullmeta.json");
+
+    std::fs::write(&part, &payload[..split]).unwrap();
+    ResumeMeta {
+        url: url.clone(),
+        etag: Some("\"v1\"".to_string()),
+        last_modified: None,
+        total: Some(payload.len() as u64),
+        algo: HashAlgo::Sha1,
+        hash: sha1_hex(&payload),
+        saved_at_ms: 1,
+    }
+    .save(&meta_path)
+    .expect("写续传元数据失败");
+
+    let outcome = harness
+        .engine
+        .download(
+            DownloadRequest::new(ResourceKind::ClientJar, url.as_str(), &dest)
+                .with_sha1(sha1_hex(&payload))
+                .with_size(payload.len() as u64),
+        )
+        .await
+        .expect("续传失败");
+
+    assert_eq!(outcome.resumed_from, split as u64, "应从已有偏移续传");
+    assert_eq!(std::fs::read(&dest).unwrap(), payload);
+    assert_eq!(server.hits(), 1);
+    server.stop();
+}
+
+#[tokio::test]
+async fn reports_progress_events_and_errors_when_all_sources_fail() {
+    let server = MockServer::start(vec![
+        MockResponse::status(500),
+        MockResponse::status(500),
+        MockResponse::status(500),
+        MockResponse::status(500),
+    ])
+    .await;
+    let url = server.url("/dead.jar");
+    let dir = temp_dir("engine-fail");
+    let cache = Arc::new(ContentCache::open(dir.join("cache")));
+    let (emitter, mut events) = ProgressEmitter::channel();
+    let engine = DownloadEngine::new(
+        fast_config(1),
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(direct_region()),
+        Arc::new(HealthRegistry::in_memory()),
+        cache,
+    )
+    .with_progress(emitter);
+
+    let error = engine
+        .download(DownloadRequest::new(
+            ResourceKind::Library,
+            url.as_str(),
+            dir.join("dead.jar"),
+        ))
+        .await
+        .expect_err("所有源都 500 时必须失败");
+    assert_eq!(error.kind, DownloadErrorKind::AllSourcesFailed);
+
+    let mut started = false;
+    let mut failed_source = false;
+    while let Ok(event) = events.try_recv() {
+        match event {
+            ProgressEvent::Started { candidates, .. } => {
+                started = true;
+                assert!(candidates >= 1);
+            }
+            ProgressEvent::SourceFailed { will_retry, .. } => {
+                failed_source = true;
+                assert!(!will_retry, "单次尝试用尽后不应再声明重试");
+            }
+            _ => {}
+        }
+    }
+    assert!(started && failed_source, "进度事件缺失");
+    server.stop();
+}

crates/core/tests/download/health_test.rs

@@ -0,0 +1,268 @@
+//! 健康度记忆的单测：冷却、恢复探测、排序、持久化 + 引擎驱动的落盘接线。
+
+mod support;
+
+use std::sync::Arc;
+use std::time::Duration;
+
+use unlucky_core::download::backoff::BackoffPolicy;
+use unlucky_core::download::cache::{now_ms, ContentCache};
+use unlucky_core::download::config::EngineConfig;
+use unlucky_core::download::engine::DownloadEngine;
+use unlucky_core::download::error::DownloadErrorKind;
+use unlucky_core::download::health::{
+    HealthRegistry, SourceHealth, COOLDOWN_MS, FAILURE_THRESHOLD,
+};
+use unlucky_core::download::mirrors::MirrorTable;
+use unlucky_core::download::region::RegionProfile;
+use unlucky_core::download::types::{Candidate, DownloadRequest, ResourceKind, SOURCE_OFFICIAL};
+
+use support::{MockResponse, MockServer};
+
+const NOW: u64 = 1_000_000;
+
+fn registry() -> HealthRegistry {
+    HealthRegistry::in_memory()
+}
+
+#[test]
+fn fresh_source_is_neutral_not_penalized() {
+    let health = SourceHealth::default();
+    assert!(!health.is_cooling_down(NOW));
+    assert_eq!(health.failure_rate(), 0.0);
+    // 未知源必须是中间分，不能比刚成功的源更优先。
+    let healthy = SourceHealth {
+        samples: 3,
+        successes: 3,
+        ema_rtt_ms: 120.0,
+        ..SourceHealth::default()
+    };
+    assert!(healthy.score(NOW) < health.score(NOW));
+}
+
+#[test]
+fn three_consecutive_failures_trigger_cooldown() {
+    let mut health = SourceHealth::default();
+    for _ in 0..FAILURE_THRESHOLD {
+        health.record_failure("HTTP 502", NOW);
+    }
+    assert!(health.is_cooling_down(NOW));
+    assert!(health.is_cooling_down(NOW + COOLDOWN_MS - 1));
+    // 冷却到期后不再是冷却态，而是「可以探测」。
+    assert!(!health.is_cooling_down(NOW + COOLDOWN_MS));
+    assert!(health.is_probe(NOW + COOLDOWN_MS));
+    // 冷却中的源排序惩罚要明显高于健康源。
+    assert!(health.score(NOW) >= 1_000.0);
+}
+
+#[test]
+fn missing_artifact_is_recorded_without_cooling_down() {
+    // 院校镜像只留最新补丁：请求旧补丁必然 404，不能把源判成「坏」。
+    let mut health = SourceHealth::default();
+    for _ in 0..(FAILURE_THRESHOLD * 2) {
+        health.record_missing("HTTP 404", NOW);
+    }
+    assert!(!health.is_cooling_down(NOW), "4xx 不进冷却");
+    assert!(!health.is_probe(NOW), "4xx 不该产生恢复探测状态");
+    assert_eq!(health.failures, 0, "4xx 不计失败次数");
+    assert_eq!(health.not_found, u64::from(FAILURE_THRESHOLD * 2));
+    assert_eq!(health.failure_rate(), 0.0);
+    assert!(health.last_error.is_some(), "诊断仍要留痕");
+    // 打分不应被 404 拉高（仍是未知源的中位分）。
+    assert_eq!(health.score(NOW), SourceHealth::default().score(NOW));
+    assert_eq!(
+        health.score(NOW),
+        unlucky_core::download::health::SCORE_UNKNOWN
+    );
+}
+
+#[test]
+fn not_found_ageing_does_not_persist_a_cooldown() {
+    let registry = HealthRegistry::in_memory();
+    for _ in 0..10 {
+        registry.record_missing("tuna", ResourceKind::JavaRuntime, "HTTP 404", NOW);
+    }
+    let health = registry.health_of("tuna", ResourceKind::JavaRuntime);
+    assert!(!health.is_cooling_down(NOW));
+    assert_eq!(health.not_found, 10);
+    assert_eq!(health.consecutive_failures, 0);
+}
+
+#[test]
+fn probe_failure_re_arms_cooldown_and_success_clears_it() {
+    let mut health = SourceHealth::default();
+    for _ in 0..FAILURE_THRESHOLD {
+        health.record_failure("timeout", NOW);
+    }
+    let after_cooldown = NOW + COOLDOWN_MS + 1;
+    assert!(!health.is_cooling_down(after_cooldown));
+    // 探测再一次失败 → 立即重新冷却。
+    health.record_failure("timeout again", after_cooldown);
+    assert!(health.is_cooling_down(after_cooldown));
+
+    // 成功则全部清零。
+    health.record_success(90, after_cooldown + 1);
+    assert!(!health.is_cooling_down(after_cooldown + 1));
+    assert!(!health.is_probe(after_cooldown + 1));
+    assert_eq!(health.consecutive_failures, 0);
+    assert_eq!(health.cooldown_until_ms, 0);
+    assert_eq!(health.last_error, None);
+}
+
+#[test]
+fn ema_smooths_latency_and_counts_samples() {
+    let mut health = SourceHealth::default();
+    health.record_success(100, NOW);
+    assert_eq!(health.ema_rtt_ms, 100.0);
+    health.record_success(200, NOW);
+    // 0.3 * 200 + 0.7 * 100 = 130
+    assert!((health.ema_rtt_ms - 130.0).abs() < 1e-9);
+    assert_eq!(health.samples, 2);
+    assert_eq!(health.successes, 2);
+}
+
+#[test]
+fn failure_rate_counts_both_sides() {
+    let mut health = SourceHealth::default();
+    health.record_success(50, NOW);
+    health.record_failure("boom", NOW);
+    assert!((health.failure_rate() - 0.5).abs() < 1e-9);
+}
+
+#[test]
+fn registry_ranks_healthy_first_and_cooling_last() {
+    let registry = registry();
+    for _ in 0..FAILURE_THRESHOLD {
+        registry.record_failure("mirror-b", ResourceKind::ClientJar, "HTTP 500", NOW);
+    }
+    registry.record_success(
+        "mirror-a",
+        ResourceKind::ClientJar,
+        Duration::from_millis(80),
+        NOW,
+    );
+
+    let candidates = vec![
+        Candidate::new("mirror-b", "https://b.example/file"),
+        Candidate::new("unknown", "https://u.example/file"),
+        Candidate::new("mirror-a", "https://a.example/file"),
+    ];
+    let ranked = registry.rank(&candidates, ResourceKind::ClientJar, NOW);
+    assert_eq!(ranked[0].source, "mirror-a");
+    assert_eq!(ranked[1].source, "unknown");
+    assert_eq!(
+        ranked[2].source, "mirror-b",
+        "冷却中的源排最后但仍保留为兜底"
+    );
+}
+
+#[test]
+fn health_is_tracked_per_resource_kind() {
+    let registry = registry();
+    for _ in 0..FAILURE_THRESHOLD {
+        registry.record_failure("bmclapi", ResourceKind::Asset, "404", NOW);
+    }
+    assert!(registry.is_cooling_down("bmclapi", ResourceKind::Asset, NOW));
+    // 另一种资源类型不受影响（资产挂了不代表 JDK 也挂）。
+    assert!(!registry.is_cooling_down("bmclapi", ResourceKind::JavaRuntime, NOW));
+}
+
+#[test]
+fn persistence_roundtrip_and_age_pruning() {
+    let dir = std::env::temp_dir().join(format!("ull-health-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("health.json");
+
+    let registry = HealthRegistry::open(&path, 7 * 24 * 3600 * 1000, NOW);
+    registry.record_failure("bmclapi", ResourceKind::Library, "HTTP 503", NOW);
+    registry.record_success(
+        "official",
+        ResourceKind::Library,
+        Duration::from_millis(55),
+        NOW,
+    );
+    registry.save().expect("持久化失败");
+
+    let reloaded = HealthRegistry::open(&path, 7 * 24 * 3600 * 1000, NOW + 1_000);
+    assert_eq!(reloaded.snapshot().len(), 2);
+    assert_eq!(
+        reloaded
+            .health_of("bmclapi", ResourceKind::Library)
+            .failures,
+        1
+    );
+    assert!(
+        reloaded
+            .health_of("official", ResourceKind::Library)
+            .ema_rtt_ms
+            > 0.0
+    );
+
+    // 超出最大保留期 → 丢弃旧记录（缓存目录被长时间放着的情况）。
+    let pruned = HealthRegistry::open(&path, 10, NOW + 60_000);
+    assert!(pruned.snapshot().is_empty());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+/// P1 回归：健康度必须由**引擎的生产路径**落盘——下载→（模拟进程退出）→重开 registry，
+/// 冷却状态与失败计数都要还在，否则「连续 3 败冷却 10 分钟」每轮启动从零学起。
+#[tokio::test]
+async fn engine_persists_health_so_a_restart_keeps_the_cooldown() {
+    let failed = || MockResponse::status(500);
+    let server = MockServer::start(vec![failed(), failed(), failed(), failed()]).await;
+    let url = server.url("/lib.jar");
+    let dir = support::temp_dir("health-engine-persist");
+    let path = dir.join("cache/health.json");
+    let now = now_ms();
+    let max_age_ms = 7 * 24 * 3600 * 1000;
+
+    let registry = Arc::new(HealthRegistry::open(&path, max_age_ms, now));
+    let engine = DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: FAILURE_THRESHOLD,
+            backoff: BackoffPolicy {
+                base_ms: 1,
+                max_ms: 2,
+                jitter_ratio: 0.0,
+                max_attempts: FAILURE_THRESHOLD,
+            },
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::clone(&registry),
+        Arc::new(ContentCache::open(dir.join("cache"))),
+    );
+
+    let error = engine
+        .download(DownloadRequest::new(
+            ResourceKind::Library,
+            url.as_str(),
+            dir.join("lib.jar"),
+        ))
+        .await
+        .expect_err("全 500 必须失败");
+    assert_eq!(error.kind, DownloadErrorKind::AllSourcesFailed);
+    server.stop();
+
+    // 第 3 次连续失败进入冷却时就该落盘（不等收尾 flush）。
+    assert!(path.is_file(), "健康度必须已经落盘到 cache/health.json");
+    let before = registry.health_of(SOURCE_OFFICIAL, ResourceKind::Library);
+    assert!(before.consecutive_failures >= FAILURE_THRESHOLD);
+    assert!(before.is_cooling_down(now_ms()));
+
+    // 「进程退出后重开」：从同一个文件恢复，冷却状态与失败计数都还在。
+    let reopened = HealthRegistry::open(&path, max_age_ms, now_ms());
+    let restored = reopened.health_of(SOURCE_OFFICIAL, ResourceKind::Library);
+    assert_eq!(restored.consecutive_failures, before.consecutive_failures);
+    assert_eq!(restored.failures, before.failures);
+    assert!(
+        restored.is_cooling_down(now_ms()),
+        "重开后仍应处于冷却：{restored:?}"
+    );
+    assert!(restored.last_error.is_some(), "失败原因也要持久化");
+
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/core/tests/download/mirrors_test.rs

@@ -0,0 +1,281 @@
+//! 镜像清单与前缀重写的单测（纯字符串，无网络）。
+
+use unlucky_core::download::adoptium::{parse_adoptium_artifact, JdkFlavor};
+use unlucky_core::download::mirrors::{host_of, source_id_for, MirrorTable, PrefixRule};
+use unlucky_core::download::region::RegionProfile;
+use unlucky_core::download::types::ResourceKind;
+
+const LIBRARIES_URL: &str =
+    "https://libraries.minecraft.net/com/google/guava/guava/32.0.0/guava-32.0.0.jar";
+const ASSET_URL: &str = "https://resources.download.minecraft.net/ab/abcdef0123456789";
+const GITHUB_URL: &str =
+    "https://github.com/AskaEth/Unlucky-Launcher/releases/download/v1.0.0/ull-windows-x64.exe";
+const ADOPTIUM_URL: &str = "https://github.com/adoptium/temurin17-binaries/releases/download/JDK17.0.13%2B11/OpenJDK17U-jdk_x64_windows_hotspot_17.0.13_11.zip";
+
+#[test]
+fn builtin_table_is_embedded_and_complete() {
+    let table = MirrorTable::builtin();
+    assert!(table.version >= 1);
+    assert!(table.rules.len() >= 10, "内置规则太少");
+    assert!(table.adoptium.len() >= 3, "院校镜像至少要 TUNA/USTC/SJTU");
+    assert!(!table.gh_proxies.is_empty());
+    assert!(table.gh_proxies[0].prefix.starts_with("https://gh-proxy"));
+}
+
+#[test]
+fn prefix_rule_preserves_sub_path() {
+    let table = MirrorTable::builtin();
+    let rule = table
+        .prefix_rule_for(LIBRARIES_URL, ResourceKind::Library)
+        .expect("libraries 规则缺失");
+    let candidate = rule.apply(LIBRARIES_URL).expect("重写失败");
+    assert_eq!(candidate.source, "bmclapi");
+    assert_eq!(
+        candidate.url,
+        LIBRARIES_URL.replace(
+            "https://libraries.minecraft.net",
+            "https://bmclapi2.bangbang93.com"
+        )
+    );
+}
+
+#[test]
+fn asset_rule_injects_path_prefix() {
+    let table = MirrorTable::builtin();
+    let candidate = table
+        .prefix_rule_for(ASSET_URL, ResourceKind::Asset)
+        .and_then(|rule| rule.apply(ASSET_URL))
+        .expect("资源对象规则缺失");
+    assert_eq!(
+        candidate.url,
+        "https://bmclapi2.bangbang93.com/assets/ab/abcdef0123456789"
+    );
+}
+
+#[test]
+fn direct_mode_puts_official_first() {
+    let table = MirrorTable::builtin();
+    let region = RegionProfile::direct(0);
+    let candidates = table.expand(LIBRARIES_URL, ResourceKind::Library, &region);
+    assert_eq!(candidates[0].source, "official");
+    assert_eq!(candidates[0].url, LIBRARIES_URL);
+    // 镜像仍然保留为兜底（官方失败时能救回来）。
+    assert!(candidates
+        .iter()
+        .any(|candidate| candidate.source == "bmclapi"));
+}
+
+#[test]
+fn mirror_first_mode_puts_mirror_first() {
+    let table = MirrorTable::builtin();
+    let region = RegionProfile::mirror_first(0);
+    let candidates = table.expand(LIBRARIES_URL, ResourceKind::Library, &region);
+    assert_eq!(candidates[0].source, "bmclapi");
+    assert_eq!(
+        candidates.last().map(|c| c.source.as_str()),
+        Some("official")
+    );
+}
+
+#[test]
+fn gh_proxy_only_for_github_hosts_in_domestic_mode() {
+    let table = MirrorTable::builtin();
+    let domestic = RegionProfile::mirror_first(0);
+    let direct = RegionProfile::direct(0);
+
+    let github = table.expand(GITHUB_URL, ResourceKind::GitHubRelease, &domestic);
+    assert!(
+        github.iter().any(|candidate| candidate.source == "gh_proxy"
+            && candidate.url.starts_with("https://gh-proxy.com/")),
+        "国内模式下 GitHub 资源必须套 gh-proxy：{github:?}"
+    );
+
+    let non_github = table.expand(LIBRARIES_URL, ResourceKind::Library, &domestic);
+    assert!(
+        non_github
+            .iter()
+            .all(|candidate| candidate.source != "gh_proxy"),
+        "非 GitHub 资源不受 gh-proxy 影响"
+    );
+
+    let github_direct = table.expand(GITHUB_URL, ResourceKind::GitHubRelease, &direct);
+    assert!(github_direct
+        .iter()
+        .all(|candidate| candidate.source != "gh_proxy"));
+}
+
+#[test]
+fn pinned_or_disabled_gh_proxy_is_respected() {
+    let table = MirrorTable::builtin();
+
+    // 用户关掉：地区档案显式不带前缀 → 一条 gh_proxy 候选都不出。
+    let off = RegionProfile::mirror_first(0).with_gh_proxy(None);
+    let candidates = table.expand(GITHUB_URL, ResourceKind::GitHubRelease, &off);
+    assert!(candidates.iter().all(|c| c.source != "gh_proxy"));
+
+    // 自定义前缀（设置项写进地区档案）。
+    let custom = RegionProfile::mirror_first(0).with_gh_proxy(Some("https://proxy.example/"));
+    let candidates = table.expand(GITHUB_URL, ResourceKind::GitHubRelease, &custom);
+    let proxy = candidates
+        .iter()
+        .find(|candidate| candidate.source == "gh_proxy")
+        .expect("自定义前缀未生效");
+    assert_eq!(proxy.url, format!("https://proxy.example/{GITHUB_URL}"));
+
+    // 清单给设置做默认值。
+    assert_eq!(table.default_gh_proxy(), Some("https://gh-proxy.com/"));
+}
+
+#[test]
+fn adoptium_artifact_parsing_and_mirror_ordering() {
+    let parsed = parse_adoptium_artifact(ADOPTIUM_URL).expect("解析 Temurin 产物名失败");
+    assert_eq!(parsed.major, "17");
+    assert_eq!(parsed.flavor, JdkFlavor::Jdk);
+    assert_eq!(parsed.arch, "x64");
+    assert_eq!(parsed.os, "windows");
+    assert!(parsed.filename.starts_with("OpenJDK17U-jdk_x64_windows"));
+
+    let table = MirrorTable::builtin();
+    let region = RegionProfile::mirror_first(0);
+    let candidates = table.expand(ADOPTIUM_URL, ResourceKind::JavaRuntime, &region);
+    let first = &candidates[0];
+    assert_eq!(first.source, "tuna");
+    assert!(
+        first
+            .url
+            .starts_with("https://mirrors.tuna.tsinghua.edu.cn/Adoptium/17/jdk/x64/windows/"),
+        "院校镜像路径不符合模板：{}",
+        first.url
+    );
+    // 官方仍在候选里（全部镜像不可达时的兜底）。
+    assert!(candidates
+        .iter()
+        .any(|candidate| candidate.source == "official"));
+}
+
+/// JRE 产物必须落到镜像的 `/jre/` 子树（否则 4 个镜像全 404，加速白费）。
+#[test]
+fn adoptium_jre_uses_jre_path_segment() {
+    let jre_url = ADOPTIUM_URL.replace("OpenJDK17U-jdk_", "OpenJDK17U-jre_");
+    let parsed = parse_adoptium_artifact(&jre_url).expect("解析 JRE 产物名失败");
+    assert_eq!(parsed.flavor, JdkFlavor::Jre);
+    assert_eq!(
+        parsed.mirror_url("https://mirrors.tuna.tsinghua.edu.cn/Adoptium"),
+        format!(
+            "https://mirrors.tuna.tsinghua.edu.cn/Adoptium/17/jre/x64/windows/{}",
+            parsed.filename
+        )
+    );
+
+    let table = MirrorTable::builtin();
+    let candidates = table.expand(
+        &jre_url,
+        ResourceKind::JavaRuntime,
+        &RegionProfile::mirror_first(0),
+    );
+    let first = &candidates[0];
+    assert_eq!(first.source, "tuna");
+    assert!(
+        first.url.contains("/17/jre/x64/windows/"),
+        "JRE 必须走 /jre/ 子树：{}",
+        first.url
+    );
+
+    // `-jre-17…` 这种兜底形态同样识别。
+    let fallback = "https://github.com/adoptium/temurin21-binaries/releases/download/jre-21.0.5%2B11/OpenJDK21U-jre_x64_linux_hotspot_21.0.5_11.tar.gz";
+    assert_eq!(
+        parse_adoptium_artifact(fallback).map(|artifact| artifact.flavor),
+        Some(JdkFlavor::Jre)
+    );
+}
+
+#[test]
+fn custom_rules_take_precedence() {
+    let mut table = MirrorTable::builtin();
+    table.add_custom_rule(PrefixRule::new(
+        "my-mirror",
+        "https://libraries.minecraft.net",
+        "https://mirror.example/libraries",
+    ));
+    let candidate = table
+        .prefix_rule_for(LIBRARIES_URL, ResourceKind::Library)
+        .and_then(|rule| rule.apply(LIBRARIES_URL))
+        .expect("自定义规则未生效");
+    assert_eq!(candidate.source, "mirror.example");
+    assert_eq!(
+        candidate.url,
+        "https://mirror.example/libraries/com/google/guava/guava/32.0.0/guava-32.0.0.jar"
+    );
+}
+
+#[test]
+fn fallback_rule_keeps_official_first_even_in_domestic_mode() {
+    let mut table = MirrorTable {
+        version: 1,
+        notes: Vec::new(),
+        rules: vec![PrefixRule::new(
+            "modrinth-accelerator",
+            "https://api.modrinth.com",
+            "https://cdn.example",
+        )
+        .fallback()],
+        // v3 新增的三张 JDK 源表在这张夹具里必须为空（否则会混进别的候选）。
+        adoptium: Vec::new(),
+        oracle_openjdk: Vec::new(),
+        microsoft_openjdk: None,
+        zulu: None,
+        gh_proxies: Vec::new(),
+    };
+    let region = RegionProfile::mirror_first(0);
+    let candidates = table.expand(
+        "https://api.modrinth.com/v2/project/sodium",
+        ResourceKind::ModFile,
+        &region,
+    );
+    assert_eq!(
+        candidates[0].source, "official",
+        "「仅加速」规则不能顶掉官方"
+    );
+    assert_eq!(candidates[1].source, "cdn.example");
+
+    // 关掉规则后只剩官方一条。
+    table.rules.clear();
+    let candidates = table.expand(
+        "https://api.modrinth.com/v2/project/sodium",
+        ResourceKind::ModFile,
+        &region,
+    );
+    assert_eq!(candidates.len(), 1);
+}
+
+#[test]
+fn host_and_source_id_helpers() {
+    assert_eq!(
+        host_of("https://libraries.minecraft.net/a/b"),
+        Some("libraries.minecraft.net")
+    );
+    assert_eq!(
+        host_of("https://user:pass@mirror.example:8443/x/y"),
+        Some("mirror.example")
+    );
+    assert_eq!(host_of("http://127.0.0.1:8080/file"), Some("127.0.0.1"));
+    assert_eq!(host_of("not-a-url"), Some("not-a-url"));
+
+    assert_eq!(
+        source_id_for("https://bmclapi2.bangbang93.com/assets/ab/cd"),
+        "bmclapi"
+    );
+    assert_eq!(
+        source_id_for("https://mirrors.tuna.tsinghua.edu.cn/Adoptium/17/x.zip"),
+        "tuna"
+    );
+    assert_eq!(
+        source_id_for("https://mirrors.ustc.edu.cn/adoptium/17/x.zip"),
+        "ustc"
+    );
+    assert_eq!(
+        source_id_for("https://gh-proxy.com/https://github.com/a/b"),
+        "gh_proxy"
+    );
+    assert_eq!(source_id_for("https://example.org/file"), "example.org");
+}

crates/core/tests/download/partfile_test.rs

@@ -0,0 +1,233 @@
+//! `download::atomic::PartFile`：中间文件的进程/实例隔离、续传收养与孤儿清理。
+//!
+//! 背景（M35 真机 finding）：中间文件路径原先只由目标路径决定，两个启动器进程装同一
+//! 数据根时共用一个 `.ullpart`，先提交的一方 `rename` 走，另一方 `os error 2`
+//! （实测两次 `ull install` 各失败 819 / 1116 个资源）。这里守住三条：名字带会话标识、
+//! 旧材料能收养、孤儿清理不许误删有人在用的中间文件。
+
+mod support;
+
+use std::fs;
+use std::io::Write;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::Duration;
+
+use unlucky_core::download::backoff::BackoffPolicy;
+use unlucky_core::download::cache::ContentCache;
+use unlucky_core::download::chunked::ChunkedConfig;
+use unlucky_core::download::config::EngineConfig;
+use unlucky_core::download::engine::DownloadEngine;
+use unlucky_core::download::health::HealthRegistry;
+use unlucky_core::download::mirrors::MirrorTable;
+use unlucky_core::download::region::RegionProfile;
+use unlucky_core::download::types::{DownloadRequest, ResourceKind};
+use unlucky_core::download::{PartFile, ADOPT_MIN_AGE, META_SUFFIX, ORPHAN_MAX_AGE, PART_SUFFIX};
+
+use support::{age_file, part_files, sha1_hex, temp_dir, MockResponse, MockServer};
+
+/// 另一个会话号（保证与本进程不同）。
+fn foreign_session() -> u32 {
+    std::process::id() ^ 1
+}
+
+fn part_name(name: &str, session: u32, seq: u64) -> String {
+    format!("{name}{PART_SUFFIX}-{session}-{seq}")
+}
+
+fn write_part(dir: &Path, name: &str) -> PathBuf {
+    let path = dir.join(name);
+    fs::write(&path, b"0123456789").expect("写中间文件失败");
+    path
+}
+
+#[test]
+fn part_file_names_carry_session_and_sequence() {
+    let dir = temp_dir("partfile-identity");
+    let dest = dir.join("client.jar");
+
+    let first = PartFile::for_dest(&dest);
+    let second = PartFile::for_dest(&dest);
+
+    assert_ne!(
+        first.path(),
+        second.path(),
+        "同一 dest 的两个守卫不能共用文件"
+    );
+    assert_eq!(first.path().parent(), Some(dir.as_path()));
+    let name = first.path().file_name().unwrap().to_string_lossy();
+    assert!(
+        name.starts_with(&format!("client.jar{PART_SUFFIX}-")),
+        "中间文件名要带进程标识：{name}"
+    );
+    assert!(
+        name.contains(&std::process::id().to_string()),
+        "进程号要在名字里（跨进程隔离的依据）：{name}"
+    );
+}
+
+#[test]
+fn two_threads_writing_the_same_dest_commit_independently() {
+    let dir = temp_dir("partfile-threads");
+    let dest = dir.join("client.jar");
+
+    let handles: Vec<_> = (0..2_u8)
+        .map(|index| {
+            let dest = dest.clone();
+            std::thread::spawn(move || {
+                let payload = vec![b'a' + index; 4096];
+                let part = PartFile::for_dest(&dest);
+                part.open_truncate()
+                    .expect("打开中间文件失败")
+                    .write_all(&payload)
+                    .expect("写中间文件失败");
+                part.commit(&dest).expect("原子落盘失败");
+                payload
+            })
+        })
+        .collect();
+
+    let payloads: Vec<Vec<u8>> = handles
+        .into_iter()
+        .map(|handle| handle.join().expect("下载线程 panic"))
+        .collect();
+    let written = fs::read(&dest).expect("读落盘文件失败");
+    assert!(
+        payloads.contains(&written),
+        "落盘内容必须是某个线程的完整产物"
+    );
+    assert!(
+        part_files(&dir).is_empty(),
+        "两线程各自的中间文件都要被提交掉：{:?}",
+        part_files(&dir)
+    );
+}
+
+#[test]
+fn legacy_part_file_is_adopted_for_resume() {
+    let dir = temp_dir("partfile-legacy");
+    let dest = dir.join("client.jar");
+    let legacy = write_part(&dir, &format!("client.jar{PART_SUFFIX}"));
+    let legacy_meta = dir.join(format!("client.jar{PART_SUFFIX}{META_SUFFIX}"));
+    fs::write(&legacy_meta, b"{}").expect("写元数据失败");
+
+    let part = PartFile::for_dest(&dest);
+
+    assert_ne!(part.path(), legacy.as_path(), "新守卫要换自己的名字");
+    assert_eq!(part.len(), 10, "旧版中间文件必须被收养（续传语义不变）");
+    assert!(!legacy.exists(), "收养后不许留下旧名字");
+    assert!(!legacy_meta.exists(), "元数据要跟着中间文件一起搬");
+    assert!(part.meta_path().is_file(), "收养后的元数据路径要就位");
+}
+
+#[test]
+fn foreign_part_file_is_adopted_only_after_it_cools_down() {
+    let dir = temp_dir("partfile-foreign");
+    let dest = dir.join("client.jar");
+    let foreign = write_part(&dir, &part_name("client.jar", foreign_session(), 1));
+
+    let fresh = PartFile::for_dest(&dest);
+    assert!(!fresh.exists(), "外进程刚写过的中间文件不能抢");
+    assert!(foreign.is_file(), "更不能删（可能正被那个进程写着）");
+
+    age_file(&foreign, ADOPT_MIN_AGE + Duration::from_secs(60));
+    let adopted = PartFile::for_dest(&dest);
+    assert_eq!(adopted.len(), 10, "静置够久的外来中间文件应被收养续传");
+    assert!(!foreign.exists(), "收养后旧名字应消失");
+}
+
+#[test]
+fn sweeps_ownerless_orphans_but_keeps_fresh_and_live_files() {
+    let dir = temp_dir("partfile-sweep");
+    let stale = write_part(&dir, &format!("other.jar{PART_SUFFIX}"));
+    let stale_meta = dir.join(format!("other.jar{PART_SUFFIX}{META_SUFFIX}"));
+    fs::write(&stale_meta, b"{}").expect("写元数据失败");
+    age_file(&stale, ORPHAN_MAX_AGE + Duration::from_secs(60));
+    let fresh = write_part(&dir, &format!("fresh.jar{PART_SUFFIX}"));
+
+    let _guard = PartFile::for_dest(&dir.join("client.jar"));
+
+    assert!(!stale.exists(), "无主且超龄的中间文件应被清理");
+    assert!(!stale_meta.exists(), "它的元数据也要一起清");
+    assert_eq!(
+        fs::read(&fresh).unwrap().len(),
+        10,
+        "还新鲜的无主文件不能删"
+    );
+}
+
+#[test]
+fn keeps_another_live_guard_of_the_same_dest() {
+    let dir = temp_dir("partfile-live");
+    let dest = dir.join("client.jar");
+    let running = PartFile::for_dest(&dest);
+    running
+        .open_truncate()
+        .expect("打开中间文件失败")
+        .write_all(&[b'x'; 1024])
+        .expect("写中间文件失败");
+
+    let other = PartFile::for_dest(&dest);
+
+    assert!(
+        running.path().is_file(),
+        "有人在用的中间文件不能被清理或收养"
+    );
+    assert_eq!(running.len(), 1024);
+    assert_ne!(other.path(), running.path());
+}
+
+fn fast_engine(cache: &Path) -> DownloadEngine {
+    DownloadEngine::new(
+        EngineConfig {
+            max_attempts_per_source: 1,
+            backoff: BackoffPolicy {
+                base_ms: 1,
+                max_ms: 2,
+                jitter_ratio: 0.0,
+                max_attempts: 1,
+            },
+            read_timeout: Duration::from_secs(5),
+            connect_timeout: Duration::from_secs(5),
+            chunked: ChunkedConfig::disabled(),
+            ..EngineConfig::default()
+        },
+        Arc::new(MirrorTable::builtin()),
+        Arc::new(RegionProfile::direct(0)),
+        Arc::new(HealthRegistry::in_memory()),
+        Arc::new(ContentCache::open(cache)),
+    )
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+async fn two_engines_downloading_the_same_dest_do_not_share_parts() {
+    let payload = b"same destination payload".to_vec();
+    let server = MockServer::start(vec![
+        MockResponse::ok(payload.clone()),
+        MockResponse::ok(payload.clone()),
+    ])
+    .await;
+    let url = server.url("/client.jar");
+    let dir = temp_dir("partfile-engine");
+    let dest = dir.join("client.jar");
+    // 两份独立的缓存目录：否则后到的那次会直接吃内容缓存，绕过中间文件路径。
+    let left = fast_engine(&dir.join("cache-a"));
+    let right = fast_engine(&dir.join("cache-b"));
+    let request = || {
+        DownloadRequest::new(ResourceKind::ClientJar, url.as_str(), &dest)
+            .with_sha1(sha1_hex(&payload))
+            .with_size(payload.len() as u64)
+    };
+
+    let (first, second) = tokio::join!(left.download(request()), right.download(request()));
+
+    first.expect("并行下载 A 失败");
+    second.expect("并行下载 B 失败");
+    assert_eq!(fs::read(&dest).expect("读落盘文件失败"), payload);
+    assert!(
+        part_files(&dir).is_empty(),
+        "并发下载不能留下中间文件：{:?}",
+        part_files(&dir)
+    );
+    server.stop();
+}

crates/core/tests/download/region_test.rs

@@ -0,0 +1,121 @@
+//! 地区判定的单测：只测纯判定与缓存，不真发探测请求。
+
+use unlucky_core::download::region::{
+    decide_from, load_cached, store_cached, RegionMode, RegionProfile, RegionTrigger, Signals,
+    DECISION_TTL_MS, DEFAULT_GH_PROXY,
+};
+
+fn signals(timezone: Option<&str>, language: Option<&str>, google: Option<bool>) -> Signals {
+    Signals {
+        timezone: timezone.map(str::to_string),
+        languages: language.map(str::to_string).into_iter().collect(),
+        google_reachable: google,
+        baidu_reachable: None,
+    }
+}
+
+#[test]
+fn timezone_signal_detects_greater_china() {
+    assert!(signals(Some("Asia/Shanghai"), None, None).is_greater_china());
+    assert!(signals(Some("Asia/Taipei"), None, None).is_greater_china());
+    // 大小写/空白容错。
+    assert!(signals(Some(" asia/hong_kong "), None, None).is_greater_china());
+    assert!(!signals(Some("Europe/Berlin"), None, None).is_greater_china());
+}
+
+#[test]
+fn language_signal_handles_posix_and_bcp47() {
+    assert!(signals(None, Some("zh_CN.UTF-8"), None).is_greater_china());
+    assert!(signals(None, Some("zh-Hant-TW"), None).is_greater_china());
+    assert!(!signals(None, Some("en_US.UTF-8"), None).is_greater_china());
+    // 时区不命中、语言命中也算。
+    assert!(signals(Some("UTC"), Some("zh_TW"), None).is_greater_china());
+}
+
+#[test]
+fn domestic_without_google_goes_mirror_first() {
+    let profile = decide_from(&signals(Some("Asia/Shanghai"), None, Some(false)), 1);
+    assert_eq!(profile.mode, RegionMode::MirrorFirst);
+    assert!(profile.greater_china);
+    assert_eq!(profile.trigger, RegionTrigger::Auto);
+    assert_eq!(profile.gh_proxy.as_deref(), Some(DEFAULT_GH_PROXY));
+    assert!(profile.gh_proxy_enabled());
+}
+
+#[test]
+fn domestic_with_google_reachable_stays_direct() {
+    // 已有全局代理：尊重用户代理，不再插镜像。
+    let profile = decide_from(&signals(Some("Asia/Shanghai"), None, Some(true)), 1);
+    assert_eq!(profile.mode, RegionMode::Direct);
+    assert!(profile.gh_proxy.is_none());
+    assert!(!profile.gh_proxy_enabled());
+}
+
+#[test]
+fn non_greater_china_is_always_direct() {
+    for google in [Some(true), Some(false), None] {
+        let profile = decide_from(&signals(Some("America/New_York"), Some("en-US"), google), 1);
+        assert_eq!(profile.mode, RegionMode::Direct, "google={google:?}");
+        assert!(!profile.greater_china);
+    }
+}
+
+#[test]
+fn probes_disabled_defaults_to_mirror_first_for_chinese_env() {
+    let profile = decide_from(&signals(None, Some("zh_CN.UTF-8"), None), 1);
+    assert_eq!(profile.mode, RegionMode::MirrorFirst);
+    assert!(!profile.probes_enabled);
+}
+
+#[test]
+fn pinned_mode_never_goes_stale() {
+    let pinned = RegionProfile::pinned(RegionMode::Direct, 10);
+    assert_eq!(pinned.trigger, RegionTrigger::UserPinned);
+    assert!(!pinned.is_stale(10 + DECISION_TTL_MS * 10));
+
+    let auto = decide_from(&signals(Some("Asia/Shanghai"), None, Some(false)), 10);
+    assert!(!auto.is_stale(10 + 1_000));
+    assert!(auto.is_stale(10 + DECISION_TTL_MS + 1));
+}
+
+#[test]
+fn gh_proxy_helpers() {
+    let mut profile = RegionProfile::mirror_first(0);
+    assert!(profile.gh_proxy_enabled());
+    profile = profile.with_gh_proxy(Some("   "));
+    assert!(!profile.gh_proxy_enabled(), "空白前缀视为不启用");
+    profile = profile.with_gh_proxy(Some("https://proxy.example/"));
+    assert!(profile.gh_proxy_enabled());
+
+    // 直连模式下即便配了前缀也不生效（gh-proxy 只在国内模式用）。
+    let direct = RegionProfile::direct(0).with_gh_proxy(Some("https://proxy.example/"));
+    assert!(!direct.gh_proxy_enabled());
+    assert_eq!(direct.label(), "直连");
+    assert_eq!(RegionProfile::mirror_first(0).label(), "镜像优先");
+}
+
+#[test]
+fn cache_roundtrip_and_ttl_expiry() {
+    let dir = std::env::temp_dir().join(format!("ull-region-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("region.json");
+
+    let profile = decide_from(&signals(Some("Asia/Shanghai"), None, Some(false)), 1_000);
+    store_cached(&path, &profile).expect("写缓存失败");
+
+    let cached = load_cached(&path, 1_000 + 60_000).expect("应有缓存");
+    assert_eq!(cached, profile);
+
+    // 过期 → 视为没有缓存。
+    assert!(load_cached(&path, 1_000 + DECISION_TTL_MS + 1).is_none());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}
+
+#[test]
+fn missing_cache_file_is_not_an_error() {
+    let path = std::env::temp_dir().join("ull-region-does-not-exist.json");
+    let _ = std::fs::remove_file(&path);
+    assert!(load_cached(&path, 0).is_none());
+}

crates/core/tests/download/resume_test.rs

@@ -0,0 +1,223 @@
+//! 断点续传保守判定的单测：矩阵覆盖 + 416 处理。
+
+use unlucky_core::download::resume::{
+    decide, on_range_unsatisfiable, RestartReason, ResumeDecision, ResumeMeta, Validator,
+};
+use unlucky_core::download::types::{HashAlgo, ResumePolicy};
+
+const URL: &str = "https://bmclapi2.bangbang93.com/versions/1.20.1/client.jar";
+const HASH: &str = "0123456789abcdef0123456789abcdef01234567";
+
+fn meta(url: &str) -> ResumeMeta {
+    ResumeMeta {
+        url: url.to_string(),
+        etag: Some("\"abc\"".to_string()),
+        last_modified: None,
+        total: Some(1_000),
+        algo: HashAlgo::Sha1,
+        hash: HASH.to_string(),
+        saved_at_ms: 1,
+    }
+}
+
+fn resume_ok(part_len: u64, meta: &ResumeMeta) -> ResumeDecision {
+    decide(
+        ResumePolicy::Conservative,
+        part_len,
+        Some(meta),
+        URL,
+        Some((HashAlgo::Sha1, HASH)),
+        Some(1_000),
+    )
+}
+
+#[test]
+fn resumes_when_everything_matches() {
+    let decision = resume_ok(400, &meta(URL));
+    assert_eq!(
+        decision,
+        ResumeDecision::Resume {
+            offset: 400,
+            validator: Validator {
+                etag: Some("\"abc\"".to_string()),
+                last_modified: None,
+            },
+        }
+    );
+}
+
+#[test]
+fn never_policy_and_missing_files_restart() {
+    let meta = meta(URL);
+    assert_eq!(
+        decide(
+            ResumePolicy::Never,
+            400,
+            Some(&meta),
+            URL,
+            Some((HashAlgo::Sha1, HASH)),
+            Some(1_000)
+        ),
+        ResumeDecision::Restart {
+            reason: RestartReason::PolicyNever
+        }
+    );
+    assert_eq!(
+        resume_ok(0, &meta),
+        ResumeDecision::Restart {
+            reason: RestartReason::EmptyPart
+        }
+    );
+    // 没有元数据：无法证明中间文件是同一次下载的产物。
+    assert_eq!(
+        decide(
+            ResumePolicy::Conservative,
+            400,
+            None,
+            URL,
+            Some((HashAlgo::Sha1, HASH)),
+            Some(1_000)
+        ),
+        ResumeDecision::Restart {
+            reason: RestartReason::NoMeta
+        }
+    );
+}
+
+#[test]
+fn changed_url_or_hash_restarts() {
+    assert_eq!(
+        decide(
+            ResumePolicy::Conservative,
+            400,
+            Some(&meta("https://other.example/client.jar")),
+            URL,
+            Some((HashAlgo::Sha1, HASH)),
+            Some(1_000)
+        ),
+        ResumeDecision::Restart {
+            reason: RestartReason::UrlChanged
+        }
+    );
+    assert_eq!(
+        decide(
+            ResumePolicy::Conservative,
+            400,
+            Some(&meta(URL)),
+            URL,
+            Some((HashAlgo::Sha1, "ffffffffffffffffffffffffffffffffffffffff")),
+            Some(1_000)
+        ),
+        ResumeDecision::Restart {
+            reason: RestartReason::HashChanged
+        }
+    );
+}
+
+#[test]
+fn unknown_total_or_oversize_restarts() {
+    let mut unknown = meta(URL);
+    unknown.total = None;
+    assert_eq!(
+        decide(
+            ResumePolicy::Conservative,
+            400,
+            Some(&unknown),
+            URL,
+            None,
+            None
+        ),
+        ResumeDecision::Restart {
+            reason: RestartReason::TotalUnknown
+        }
+    );
+
+    assert_eq!(
+        resume_ok(2_000, &meta(URL)),
+        ResumeDecision::Restart {
+            reason: RestartReason::Oversize
+        }
+    );
+}
+
+#[test]
+fn complete_part_skips_transfer() {
+    assert_eq!(
+        resume_ok(1_000, &meta(URL)),
+        ResumeDecision::Complete { size: 1_000 }
+    );
+}
+
+#[test]
+fn missing_validator_restarts() {
+    let mut weak = meta(URL);
+    weak.etag = None;
+    weak.last_modified = None;
+    assert_eq!(
+        resume_ok(400, &weak),
+        ResumeDecision::Restart {
+            reason: RestartReason::NoValidator
+        }
+    );
+    // Last-Modified 单独也能当校验器。
+    weak.last_modified = Some("Wed, 21 Oct 2015 07:28:00 GMT".to_string());
+    assert!(matches!(
+        resume_ok(400, &weak),
+        ResumeDecision::Resume { offset: 400, .. }
+    ));
+}
+
+#[test]
+fn expected_size_can_stand_in_for_missing_total() {
+    let mut unknown = meta(URL);
+    unknown.total = None;
+    let decision = decide(
+        ResumePolicy::Conservative,
+        400,
+        Some(&unknown),
+        URL,
+        Some((HashAlgo::Sha1, HASH)),
+        Some(1_000),
+    );
+    assert!(matches!(
+        decision,
+        ResumeDecision::Resume { offset: 400, .. }
+    ));
+}
+
+#[test]
+fn range_not_satisfiable_handling() {
+    // 已下满：直接进入校验，不要白删一个好文件。
+    assert_eq!(
+        on_range_unsatisfiable(1_000, Some(1_000)),
+        ResumeDecision::Complete { size: 1_000 }
+    );
+    // 没下满却 416：中间文件不可信，丢掉重来。
+    let decision = on_range_unsatisfiable(400, Some(1_000));
+    assert_eq!(
+        decision,
+        ResumeDecision::Restart {
+            reason: RestartReason::RangeUnsatisfiable
+        }
+    );
+    assert!(decision.should_drop_part());
+    // 不允许丢掉「已完成」的中间文件。
+    assert!(!ResumeDecision::Complete { size: 1 }.should_drop_part());
+}
+
+#[test]
+fn resume_meta_roundtrip_and_removal() {
+    let dir = std::env::temp_dir().join(format!("ull-resume-{}", std::process::id()));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).unwrap();
+    let path = dir.join("client.jar.ullpart.ullmeta.json");
+
+    let original = meta(URL);
+    original.save(&path).expect("写元数据失败");
+    assert_eq!(ResumeMeta::load(&path), Some(original));
+
+    ResumeMeta::remove(&path);
+    assert!(ResumeMeta::load(&path).is_none());
+
+    let _ = std::fs::remove_dir_all(&dir);
+}

crates/core/tests/download/support/mod.rs

@@ -0,0 +1,278 @@
+//! 测试支撑：临时目录、摘要工具、进程内极简 HTTP 服务器（零额外依赖）。
+//!
+//! 为什么自己写 mock server 而不用 wiremock：P0 阶段控制依赖面（Win7 Tier-3 构建 +
+//! 单文件体积），一个 60 行的 `TcpListener` 足够表达「成功 / 500 / 校验不符 / 无视 Range」。
+
+#![allow(dead_code)]
+
+use std::net::SocketAddr;
+use std::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Arc;
+
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use tokio::net::{TcpListener, TcpStream};
+
+/// 断言用的小工具：唯一临时目录（进程内计数 + 时间戳，避免并行测试互相踩）。
+pub fn temp_dir(tag: &str) -> std::path::PathBuf {
+    static COUNTER: AtomicUsize = AtomicUsize::new(0);
+    let unique = COUNTER.fetch_add(1, Ordering::Relaxed);
+    let stamp = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .map_or(0, |since| since.as_nanos());
+    let dir = std::env::temp_dir().join(format!("ull-download-test-{tag}-{stamp}-{unique}"));
+    let _ = std::fs::remove_dir_all(&dir);
+    std::fs::create_dir_all(&dir).expect("创建临时目录失败");
+    dir
+}
+
+/// 算一段字节的 SHA-1（测试断言用）。
+pub fn sha1_hex(bytes: &[u8]) -> String {
+    use sha1::Digest;
+    let digest = sha1::Sha1::digest(bytes);
+    let mut out = String::with_capacity(40);
+    for byte in digest {
+        out.push_str(&format!("{byte:02x}"));
+    }
+    out
+}
+
+/// 目录里（不含子目录）所有中间文件家族的名字（`.ullpart` 与 `.ullmeta.json`）。
+pub fn part_files(dir: &std::path::Path) -> Vec<String> {
+    let Ok(entries) = std::fs::read_dir(dir) else {
+        return Vec::new();
+    };
+    let mut names: Vec<String> = entries
+        .flatten()
+        .map(|entry| entry.file_name().to_string_lossy().into_owned())
+        .filter(|name| name.contains(unlucky_core::download::PART_SUFFIX))
+        .collect();
+    names.sort();
+    names
+}
+
+/// 把文件的修改时间挪到「`age` 之前」（清理/收养的年龄判定用）。
+pub fn age_file(path: &std::path::Path, age: std::time::Duration) {
+    let times = std::fs::FileTimes::new().set_modified(std::time::SystemTime::now() - age);
+    std::fs::File::options()
+        .write(true)
+        .open(path)
+        .expect("打开待改 mtime 的文件失败")
+        .set_times(times)
+        .expect("改 mtime 失败");
+}
+
+/// mock 服务器给一次请求的应答。
+#[derive(Debug, Clone)]
+pub struct MockResponse {
+    /// HTTP 状态码。
+    pub status: u16,
+    /// 响应体。
+    pub body: Vec<u8>,
+    /// 是否声明 `Accept-Ranges: bytes` 并在收到 `Range` 时真的切段。
+    pub range_support: bool,
+    /// `ETag`（续传测试用）。
+    pub etag: Option<String>,
+    /// 返回 206 时故意把 `Content-Range` 写成从 0 开始（模拟段错位的坏服务器）。
+    pub lie_content_range: bool,
+}
+
+impl MockResponse {
+    /// 200 + 完整内容（支持 Range）。
+    pub fn ok(body: impl Into<Vec<u8>>) -> Self {
+        Self {
+            status: 200,
+            body: body.into(),
+            range_support: true,
+            etag: Some("\"v1\"".to_string()),
+            lie_content_range: false,
+        }
+    }
+
+    /// 固定状态码 + 空体。
+    pub fn status(status: u16) -> Self {
+        Self {
+            status,
+            body: Vec::new(),
+            range_support: false,
+            etag: None,
+            lie_content_range: false,
+        }
+    }
+
+    /// 声明不支持 Range（模拟部分镜像）。
+    pub fn without_range(mut self) -> Self {
+        self.range_support = false;
+        self
+    }
+
+    /// 206 但 `Content-Range` 谎报（模拟段错位的坏 CDN）。
+    pub fn with_wrong_content_range(mut self) -> Self {
+        self.lie_content_range = true;
+        self
+    }
+}
+
+/// 进程内极简 HTTP/1.1 服务器：按脚本顺序返回响应，脚本用尽后一律 500。
+pub struct MockServer {
+    addr: SocketAddr,
+    hits: Arc<AtomicUsize>,
+    handle: tokio::task::JoinHandle<()>,
+}
+
+impl MockServer {
+    /// 启动服务器（脚本是「每次请求一个响应」的队列）。
+    pub async fn start(script: Vec<MockResponse>) -> Self {
+        let listener = TcpListener::bind("127.0.0.1:0")
+            .await
+            .expect("绑定端口失败");
+        let addr = listener.local_addr().expect("取本地地址失败");
+        let hits = Arc::new(AtomicUsize::new(0));
+        let script = Arc::new(std::sync::Mutex::new(script));
+        let counter = Arc::clone(&hits);
+
+        let handle = tokio::spawn(async move {
+            loop {
+                let Ok((stream, _)) = listener.accept().await else {
+                    break;
+                };
+                let script = Arc::clone(&script);
+                let counter = Arc::clone(&counter);
+                tokio::spawn(async move {
+                    let index = counter.fetch_add(1, Ordering::Relaxed);
+                    let response = {
+                        let script = script.lock().unwrap_or_else(|err| err.into_inner());
+                        script.get(index).cloned()
+                    };
+                    let response = response.unwrap_or_else(|| MockResponse::status(500));
+                    let _ = serve(stream, response).await;
+                });
+            }
+        });
+
+        Self { addr, hits, handle }
+    }
+
+    /// 第 `index` 个请求该用的 URL（换成不同路径可模拟「不同源」）。
+    pub fn url(&self, path: &str) -> String {
+        format!("http://{}{}", self.addr, path)
+    }
+
+    /// 换 host 拼 URL（用 `localhost` vs `127.0.0.1` 造出两个不同源）。
+    pub fn url_with(&self, host: &str, path: &str) -> String {
+        format!("http://{host}:{}{}", self.addr.port(), path)
+    }
+
+    /// 端口号。
+    pub fn port(&self) -> u16 {
+        self.addr.port()
+    }
+
+    /// 已收到的请求数。
+    pub fn hits(&self) -> usize {
+        self.hits.load(Ordering::Relaxed)
+    }
+
+    /// 关停。
+    pub fn stop(self) {
+        self.handle.abort();
+    }
+}
+
+async fn serve(mut stream: TcpStream, response: MockResponse) -> std::io::Result<()> {
+    let mut buffer = Vec::new();
+    let mut chunk = [0_u8; 1024];
+    loop {
+        let read = stream.read(&mut chunk).await?;
+        if read == 0 {
+            break;
+        }
+        buffer.extend_from_slice(&chunk[..read]);
+        if buffer.windows(4).any(|window| window == b"\r\n\r\n") {
+            break;
+        }
+    }
+    let request = String::from_utf8_lossy(&buffer).to_ascii_lowercase();
+    let range = request
+        .lines()
+        .find_map(|line| line.strip_prefix("range: bytes="))
+        .map(str::trim)
+        .and_then(parse_range_header);
+
+    let total = response.body.len() as u64;
+    let (status, headers, body) = match (range, response.range_support) {
+        (Some((start, requested_end)), true) if start < total => {
+            // 尊重请求里的结束偏移（分块下载必须逐段精确，否则组装后长度对不上）。
+            let end = requested_end.unwrap_or(total - 1).min(total - 1);
+            let slice = response.body[start as usize..=end as usize].to_vec();
+            // 谎报模式：body 仍是正确的那一段，但头部声称从 0 开始（长度恰好 → 只有
+            // 严格比对 Content-Range 才抓得住）。
+            let (claimed_start, claimed_end) = if response.lie_content_range {
+                (0, slice.len().saturating_sub(1) as u64)
+            } else {
+                (start, end)
+            };
+            (
+                206,
+                vec![
+                    format!("Content-Range: bytes {claimed_start}-{claimed_end}/{total}"),
+                    format!("Content-Length: {}", slice.len()),
+                    "Accept-Ranges: bytes".to_string(),
+                ],
+                slice,
+            )
+        }
+        (Some(_), true) => (
+            416,
+            vec![
+                format!("Content-Range: bytes */{total}"),
+                "Content-Length: 0".to_string(),
+            ],
+            Vec::new(),
+        ),
+        _ => {
+            let mut headers = vec![format!("Content-Length: {total}")];
+            if response.range_support {
+                headers.push("Accept-Ranges: bytes".to_string());
+            }
+            (response.status, headers, response.body.clone())
+        }
+    };
+    let mut head = format!("HTTP/1.1 {status} {}\r\n", reason(status));
+    if let Some(etag) = &response.etag {
+        head.push_str(&format!("ETag: {etag}\r\n"));
+    }
+    for header in headers {
+        head.push_str(&header);
+        head.push_str("\r\n");
+    }
+    head.push_str("Connection: close\r\n\r\n");
+    stream.write_all(head.as_bytes()).await?;
+    stream.write_all(&body).await?;
+    stream.flush().await?;
+    Ok(())
+}
+
+/// 解析 `Range: bytes=<start>-<end>`（`end` 可缺省 = 到文件末尾）。
+fn parse_range_header(value: &str) -> Option<(u64, Option<u64>)> {
+    let (start, end) = value.split_once('-')?;
+    let start = start.trim().parse::<u64>().ok()?;
+    let end = end.trim();
+    let end = if end.is_empty() {
+        None
+    } else {
+        Some(end.parse::<u64>().ok()?)
+    };
+    Some((start, end))
+}
+
+fn reason(status: u16) -> &'static str {
+    match status {
+        200 => "OK",
+        206 => "Partial Content",
+        404 => "Not Found",
+        416 => "Range Not Satisfiable",
+        500 => "Internal Server Error",
+        503 => "Service Unavailable",
+        _ => "Status",
+    }
+}