fix: #278 package identity convergence — index side + dependency side (0.0.105) (#279)

* docs: embedded platform support design (#276)

Design/proposal doc for entering the embedded Linux ecosystem, restructured
as decisions-first (with rationale) then supporting detail.

Positioning: mcpp brings its own matched-libc cross compiler (latest GCC) and
consumes an external device sysroot — it is NOT a distro builder and never
adapts per-vendor SDK. The single core change is opening the sysroot seam (L2);
the CLibMode::Sysroot mechanism and the hermetic allow-list already accept
tc.sysroot, so it's a minimal insertion. pkg-config and qemu cross test-run are
xlings provisioning + thin wiring.

Locks the maintainer decision register (16 decisions + rationale), incl.:
- C++ source-only; binary interop C-ABI only + wrapper; vendor C++-only libs via
  a user-built C-bridge .so (built in vendor ABI, pure-C boundary)
- glibc baseline pinned low when building payloads (GCC version x glibc decoupled);
  payloads use the latest GCC (16), GCC 15 is only the import-std capability floor
- dropped: L4 backend mode, sysroot pinning/mgmt, .pc synthesis, and the
  "compiler doesn't support C++23" diagnostic (config II makes that case
  architecturally impossible)

Beachhead: Raspberry Pi aarch64. Net work: P0 sysroot seam + matched-libc
low-glibc GCC 16 payloads (+ one glibc-floor validation); P1 pkg-config + qemu
test-run.

Supersedes the earlier issue-276 analysis note (renamed to a proper design doc).

* fix: #278 package identity convergence — index side + dependency side (0.0.105)

mcpp-index changed `chriskohlhoff.asio`'s `name` from "chriskohlhoff.asio" to
"asio" (namespace untouched). Lint went green; all three platform workspace
jobs died after 20-58 minutes with E_NOT_FOUND. The descriptor parsed, passed
mcpp's own identity gate, and no consumer spelling could install it.

Root cause is a split in how package identity is spoken on the two sides:

  index side  — identity normalization treats (ns="a", name="b") and
                (ns="a", name="a.b") as equivalent, while install-target
                construction hard-assumes the latter. The index is a FLAT key
                space keyed by the LITERAL package.name (libxpkg: build_index
                is called with no namespace, lookup is exact entries.find),
                so the two never meet.

  dependency side — the bare-name candidate ladder's discovery rung was
                specified as "match by name across the precedence path" but
                implemented as "try two more filenames", and a total miss fell
                through to candidates.front() SILENTLY, so mcpp continued with
                a namespace it had invented.

Both contracts existed only as prose comments. They are now predicates.

INV-NAME (index side): package.name must BE the fully-qualified name whenever
package.namespace is declared. One predicate, two call sites — `mcpp xpkg
parse` (index CI, seconds) and the install path (catches descriptors that
never passed through lint, zero extra I/O since the descriptor is already in
memory). The predicate is deliberately narrow: written as the general
"literal != derived fqname" comparison it would flag the working compat-alias
path and break every bare dependency. CompatAliasIsClean locks that.

INV-RESOLVE (dependency side): a bare name resolves in exactly three places —
mcpplibs, compat, and no-namespace upstream packages. Everything else must be
written out. Global short-name search is rejected: it makes resolution depend
on which indices happen to be present, so adding an index could silently
retarget an existing dependency.

BREAKING: bare names no longer reach third-party namespaces. The index-wide
scan survives only as a did-you-mean on the already-failed path — result goes
into error text, never back into resolution.

Also fixes the generator that produced these descriptors: `mcpp emit xpkg`
wrote a bare name and no namespace at all, so filing a package into a
namespaced index meant hand-adding `namespace = "<org>"` — and that edit is
what created the split form. aimol.tensorvia-cpu was born exactly this way.
Prescribed in 2026-06-26 design §4.5; never landed until now.

Design: .agents/docs/2026-07-25-issue278-descriptor-name-form-canonicalization-design.md

Fixes #278

* docs: check off #278 implementation plan; record T6/T8 actual outcomes

* test(e2e): assert compat search path at resolution layer, not on a successful fetch

* fix: keep the lazy-git-index fall-through out of the new hard failure

A custom git index is cloned by xlings during install, so at candidate-
selection time its descriptors may legitimately not be on disk yet.
"Not found" is not conclusive there, and turning it into a hard error
would reject a package that materializes a moment later. Builtin and
local path indices are both readable at selection time, so they keep
the strict rule.

* chore: bump MCPP_VERSION constant to 0.0.105

mcpp.toml and src/toolchain/fingerprint.cppm are two independent version
sources; bumping only the manifest left `mcpp --version` reporting the
old number, which 01_help_and_version.sh cross-checks against mcpp.toml.

* docs: record #278 measured verification results and the two implementation-time corrections

Author: Sunrisepeak

.agents/docs/2026-06-26-identity-first-resolution-no-filename.md

@@ -2,7 +2,14 @@
 
 **Date:** 2026-06-26
 **Status:** Step 0 landed in v0.0.67 (candidate selection is now identity-first);
-§5 `PackageLocator` / `IdentityIndex` choke-point consolidation remains follow-up
+§5 `PackageLocator` / `IdentityIndex` choke-point consolidation remains follow-up.
+**Partly superseded by #278 (v0.0.105):** §4.5's emit half landed (`mcpp emit xpkg`
+now writes both `namespace` and the FQN `name`); its "catalog keys on canonical
+(ns,name)" half is **unachievable as written** — the catalog belongs to xlings, is
+keyed by the literal `package.name` with exact `find()`, and mcpp's normalization
+has no authority over it, so the split/FQN equivalence is instead resolved by
+constraining the wire key's spelling (INV-NAME). §4.6(c)'s discovery rung is
+narrowed — see the SUPERSEDED note at that row.
 **Extends:** [`2026-06-20-package-resolution-architecture.md`](2026-06-20-package-resolution-architecture.md)
 (realizes its deferred §5 `PackageLocator` / identity-indexed slow path),
 [`2026-05-11-namespace-field-design.md`](2026-05-11-namespace-field-design.md),
@@ -389,7 +396,30 @@ declared `(∅, a.b.c)` in the `a.b`-owned index. The user's point, encoded.
 | candidate kind | rule | matches `(aimol, tensorvia-cpu)`? |
 |---|---|---|
 | qualified, ns non-empty | **exact tuple equality** `cand == declared` | `(aimol, tensorvia-cpu)` ✅ · `(mcpplibs.aimol, …)` ❌ · `(mcpplibs, …)` ❌ |
-| discovery, ns = `∅` | match by `name` alone across the precedence path; **resolve to the declared `(ns, name)`** before returning | `(∅, tensorvia-cpu)` ✅ → resolves to `(aimol, tensorvia-cpu)` |
+| discovery, ns = `∅` | ~~match by `name` alone across the precedence path~~ **SUPERSEDED — see the note below**; **resolve to the declared `(ns, name)`** before returning | ~~`(∅, tensorvia-cpu)` ✅ → resolves to `(aimol, tensorvia-cpu)`~~ |
+
+> **SUPERSEDED by #278 (mcpp 0.0.105).** The discovery rung is **not** a
+> cross-namespace wildcard. It is the "upstream package that declares no
+> `namespace`" rung, and a hit whose descriptor declares a non-empty namespace is
+> now REJECTED at the dependency-resolution call site (`selectDependencyCandidate`
+> in `prepare.cppm`; the gate itself is unchanged, because `mcpp new --template X`
+> still discovers by short name). A bare `[dependencies]` key therefore resolves in
+> exactly three places: `mcpplibs`, `compat`, and no-namespace upstream packages.
+>
+> Why the reversal: "match by name alone across the precedence path" makes
+> resolution depend on which indices happen to be present. Two namespaces owning
+> the same short name would be settled by an index ordering that has **no total
+> order** across user-added `[indices]`, and adding an index could silently
+> retarget an existing dependency. Reproducibility beats the convenience.
+>
+> The **P3 half of this row still stands and is now actually implemented**: a
+> discovery hit writes back the namespace the DESCRIPTOR declares, not the
+> candidate's empty one. Caveat: an empty declared namespace is a legal identity
+> for upstream bare packages, not a hole to fill — the "no empty namespace ever
+> reaches the install layer" claim in §4.4 presumes §4.1 index-owned namespace
+> attribution, which remains unimplemented.
+>
+> See `.agents/docs/2026-07-25-issue278-descriptor-name-form-canonicalization-design.md` §3.2.
 
 **Selection** = first candidate (in the §(a) order) that finds a declared identity by
 rule §(c). Crucially, "finds" means **an entry with that declared identity exists in

.agents/docs/2026-07-25-issue278-descriptor-name-form-canonicalization-design.md

@@ -0,0 +1,59 @@
+# #278 包身份双侧收敛 — Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** 实现 `.agents/docs/2026-07-25-issue278-descriptor-name-form-canonicalization-design.md` 的两条不变式 → 单 PR(`Fixes #278`)→ CI 全绿 → bypass squash 合入 → 0.0.105 release → xlings 全生态验证。
+
+**Architecture:** 一个纯谓词 `xpkg_name_form_violation` 两处调用(lint + 运行期),消灭"同一决策两处推导";依赖侧候选阶梯收敛为封闭三档,全索引扫描降级为**仅失败路径**的 did-you-mean 诊断,绝不回灌解析。
+
+## Global Constraints
+
+- `canonical_xpkg_identity` / `xpkg_lua_identity_matches` **一个字不改** —— 收紧只发生在发布侧(lint)与依赖解析调用点。
+- 谓词必须收窄为"声明了非空 namespace 且 name 不以 `ns.` 开头",**不得**写成"字面 name != 推导 fqname"通用比较(会打断裸 `gtest` → `compat.gtest`)。
+- did-you-mean 扫描三约束:仅失败路径触发、只进错误文案、扫描空不改退出码。
+- 无 `namespace` 声明的上游包(`opencv`/`musl-gcc`)空 ns 是**合法身份**,T10 不得强行填充。
+- T11 收紧 scoped 到 `selectDependencyCandidate`,不动闸门(保 `mcpp new --template`)。
+- 既有单测与 e2e(160 例)全绿。
+
+## Tasks
+
+### C1 索引侧谓词与两个调用点
+
+- [x] **T1** `xpkg_name_form_violation(declaredNs, declaredName)` + `_from_lua` 导出(`src/manifest/xpkg.cppm`)
+- [x] **T2** `mcpp xpkg parse` 接入谓词,违规 exit 1;`--json` 输出 `error` 字段(`src/cli/cmd_xpkg.cppm`)
+- [x] **T3** `loadVersionDep` install 分支 fail-fast;已解析到安装物的路径 `ui::warn`(`src/build/prepare.cppm`)
+
+### C2 生成源
+
+- [x] **T4** `emit_xpkg` 输出 `namespace` + FQN `name`;无 namespace 时 stderr 提示;`--namespace` 覆盖开关(`src/pm/publisher.cppm` + emit CLI)
+
+### C3 依赖侧收敛
+
+- [x] **T9** `selectDependencyCandidate` 全候选落空 → 明确失败(`prepare.cppm:1516-1541`)
+- [x] **T10** discovery 档命中后 `extract_xpkg_namespace(*lua)` 回填真实 ns(声明为空则保持空)
+- [x] **T11** discovery 档拒绝声明了非空 `namespace` 的描述符
+- [x] **T12** did-you-mean:仅失败路径的全索引扫描,三约束写进实现注释
+
+### C4 测试
+
+- [x] **T5a** 单测:谓词 6 例(含 `CompatAliasIsClean` 回归锁)
+- [x] **T5b** 单测:依赖侧解析(三档成功 / 第三方 ns 裸名失败 / P3 空 ns 锁)
+- [x] **T5c** e2e:split 描述符 → 秒级自解释失败;改 FQN → 通过
+- [x] **T5d** e2e:裸名请求第三方 ns 包 → 失败 + did-you-mean;改写后通过
+
+### C5 文档与版本
+
+- [x] **T13** 用户文档 §2.5(`docs/05-mcpp-toml.md` + `docs/zh/05-mcpp-toml.md`)
+- [x] **T14** CHANGELOG 0.0.105 段(含 breaking:裸名不再解析第三方命名空间包)
+- [x] **T15** `mcpp.toml` version → 0.0.105
+- [x] **T11b** 修订 `2026-06-26 §4.4/§4.6(a)` 表述;更新 `prepare.cppm:1456-1459` 注释
+
+### C6 验收与合入
+
+- [x] **T6** 全索引 `mcpp xpkg parse` 回归,结果贴 PR。**实测 49/49 mcpplibs 描述符全过、0 违规**(非设计预期的 2 —— 上游 mcpp-index 已先行修好两例);完整 registry(200+)另见 §2.1b 的 xlings-native 修正
+- [ ] **T7** 单 PR(`Fixes #278`)→ CI 全绿 → `gh pr merge --squash --admin`
+
+### C7 生态
+
+- [ ] **T16** release 0.0.105 四平台 + 镜像 xlings-res 双端 + xim-pkgindex PR + `xlings install mcpp` 真装验证
+- [x] **T8** mcpp-index:**上游已完成** —— `chriskohlhoff.asio` / `tensorvia-cpu` 均已是 FQN,#116 的 `tests/check_package_name.lua` 已合入。该 Lua 守卫现与 `mcpp xpkg parse` 冗余但无害,可留作保险(其 CI 本就跑 `mcpp xpkg parse pkgs/*/*.lua`,升级 MCPP_VERSION 到 0.0.105 后自动获得引擎侧防护)

.agents/docs/2026-07-25-issue278-implementation-plan.md

@@ -3,6 +3,30 @@
 > 本文件追踪 `mcpp-community/mcpp` 公开仓的版本演进。
 > 格式参考 [Keep a Changelog](https://keepachangelog.com/zh-CN/1.1.0/)。
 
+## [0.0.105] — 2026-07-25
+
+> 包身份口径双侧收敛(#278)。事故:mcpp-index 把 `chriskohlhoff.asio` 的 `name` 从 `"chriskohlhoff.asio"` 改成 `"asio"`(namespace 不变),lint 全绿,三个平台的 workspace job 跑满 20~58 分钟后全挂 `E_NOT_FOUND` —— 描述符能解析、能过 mcpp 的身份闸门,却没有任何消费写法能装上。根因是身份归一化(容忍三种拼写)与安装目标构造(只支持一种)口径断层,契约只写在注释里、无人执行。设计见 `.agents/docs/2026-07-25-issue278-descriptor-name-form-canonicalization-design.md`。
+
+### ⚠️ 破坏性变更
+
+- **裸依赖名不再解析到第三方命名空间的包。** 命名空间缺省时,`[dependencies]` 里的裸名**只**解析三类:`mcpplibs`(默认)、`compat`(包装)、无 `namespace` 声明的上游包。此前裸名会跨命名空间命中(例如裸 `tensorvia-cpu` 能装上 `aimol` 下的包),现在必须写全:`"aimol.tensorvia-cpu" = "…"` 或 `[dependencies.aimol] tensorvia-cpu = "…"`。
+  取舍理由:全域按名发现的便捷性换来三条稳定性损失——同名包的裁决依赖索引优先级(而用户 `[indices]` 添加的索引之间**无全序**)、**新增一个索引可能悄悄改变既有依赖解析到的包**(供应链隐患)、同一份 `mcpp.toml` 在不同机器上可能解析到不同包。依赖解析的可复现性优先于书写便捷性。
+  迁移无需查文档:失败时 mcpp 会扫描索引并直接给出应当改写成的那两行(见下)。
+
+### 新增
+
+- **INV-NAME 校验(`mcpp xpkg parse`)**:描述符声明了非空 `package.namespace` 时,`package.name` 必须是完全限定名(以 `<namespace>.` 开头),否则报错退出。索引是以 `package.name` **字面值**为键的扁平空间,而 mcpp 按 `<ns>.<short>` 寻址,两者不相交即永久不可安装。诊断直接给出应写的字面量(`fix: name = "chriskohlhoff.asio"`),`--json` 同步 `error` 字段供索引 CI 机读。mcpp-index 的 CI 本就跑 `mcpp xpkg parse pkgs/*/*.lua`,免费获得秒级防护。
+- **`mcpp xpkg parse --allow-split-name`**:跳过 INV-NAME 检查。xlings 原生索引(xim-pkgindex、-scode)里 `package.namespace` 是**安装目录分类**(`config`/`scode`/`awesome`)而非包命名空间,索引按裸 `package.name` 建键,split 形式在那个世界里是正确的——这些树用此开关 lint。
+- **运行期 fail-fast**:`mcpp build` 在构造安装目标**之前**用同一个谓词校验手上已有的描述符(零额外 I/O),把"三平台一小时后的 E_NOT_FOUND"变成秒级自解释失败。lint 与运行期共用一份判定,不会再各自推导。已装旧快照的路径降级为 warning,让"本机绿、干净 CI 红"的遮蔽陷阱可见。
+- **依赖解析失败的 did-you-mean**:候选全部落空时(且**仅**在此时)扫描索引,若该短名存在于其他命名空间,直接列出 FQN 与两种可直接抄写的正确写法。该扫描是**纯诊断**——结果只进错误文案,绝不回灌解析、lockfile 或安装层(否则就退化成被否决的全域模糊匹配)。
+- **`mcpp emit xpkg --namespace <NS>`**:为归档场景提供命名空间,无需改 `mcpp.toml`。
+
+### 修复
+
+- **`mcpp emit xpkg` 不再生成破损雏形**:此前只写裸 `name`、完全不输出 `namespace`,维护者归档进命名空间索引时手补一行 `namespace = "<org>"`,那一刻描述符就变成无法安装的 split 形式(`aimol.tensorvia-cpu` 正是这么来的,文件头还留着"AUTO-GENERATED, do not edit by hand")。现在 `[package] namespace` 非空时同时输出 `namespace` 与 FQN `name`;为空时给出明确警告,说明不要事后手补。此修复在 2026-06-26 设计 §4.5 里就已写明,一直未落地。
+- **依赖候选全部落空时不再静默回退**:此前会退到第一个候选并把 mcpp **自己编造的**命名空间当作结论继续跑,失败被推迟到下载/安装阶段,错误文本里还带着用户从未写过的命名空间。现在当场失败并列出试过的每一个身份。
+- **discovery 档不再泄漏空命名空间(P3)**:`(∅, name)` 命中后写回的是**描述符声明的**命名空间,而非候选的空值——空命名空间此前会流进 lockfile 与安装层。无 `namespace` 声明的上游包(`opencv`/`musl-gcc`)保持空命名空间,那是它们的合法身份。
+
 ## [0.0.104] — 2026-07-24
 
 > `mcpp test` 能力批次(两轮):逐测试编译隔离、子目录路径命名、过滤器、JSON 输出——四项均为通用能力(cargo/ctest 同形),首个下游消费者是 d2mcpp「练习即测试」重设计(见 d2mcpp 仓 `.agents/docs/2026-07-23-exercises-as-tests-design.md` §4,验收标准即出自该文档)。实施计划见 `.agents/docs/2026-07-23-test-isolation-json-plan.md`。

CHANGELOG.md

@@ -321,6 +321,61 @@ baz = "=1.2.3"      # Exact match
 qux = ">=1.0, <2.0" # Range combination
 ```
 
+#### Namespace resolution rules
+
+Every package has a two-part identity: a **namespace** and a **name**. How you write
+a dependency key decides which namespaces mcpp will look in.
+
+**A bare name resolves in exactly three places**, in order:
+
+| # | Namespace | Example |
+|---|---|---|
+| 1 | `mcpplibs` — the default namespace | `cmdline = "0.0.2"` |
+| 2 | `compat` — the wrapper namespace for third-party C/C++ libraries | `gtest = "1.15.2"` → `compat.gtest` |
+| 3 | upstream packages that declare no namespace at all | `opencv = "4.10.0"` |
+
+**Any other namespace must be written out in full.** There is no fuzzy, index-wide
+search by short name:
+
+```toml
+# ✅ Correct — dotted selector
+[dependencies]
+"chriskohlhoff.asio" = "1.38.1"
+
+# ✅ Correct — namespace sub-table (preferred when you have several from one org)
+[dependencies.chriskohlhoff]
+asio = "1.38.1"
+
+# ❌ Wrong — a bare name never reaches the `chriskohlhoff` namespace
+[dependencies]
+asio = "1.38.1"
+```
+
+The third form fails with an error that lists the namespaces that were searched and,
+when a package with that short name exists elsewhere, the exact line to write instead.
+
+**Why not resolve bare names across every namespace?** Because dependency resolution
+has to be reproducible. A global short-name search would mean that (a) two namespaces
+owning the same short name are settled by index ordering, and (b) **adding an index
+could silently change which package an existing dependency resolves to**. Requiring
+the namespace keeps a `mcpp.toml` resolving to the same packages on every machine.
+
+**For xpkg authors:** in an index descriptor, `package.name` must be the *fully
+qualified* name — it has to start with `package.namespace` followed by a dot:
+
+```lua
+package = {
+    namespace = "chriskohlhoff",
+    name      = "chriskohlhoff.asio",   -- NOT "asio"
+    ...
+}
+```
+
+The package index is a flat key space keyed by the literal `package.name`, so the
+namespace has to be carried in the name itself — otherwise `mcpplibs`'s `zlib` and
+`compat`'s `zlib` would collide. A descriptor that gets this wrong parses fine but can
+never be installed. `mcpp xpkg parse` checks it, so run it in your index CI.
+
 ### 2.6 `[dev-dependencies]` — Test Dependencies
 
 ```toml

docs/05-mcpp-toml.md

@@ -293,6 +293,50 @@ baz = "=1.2.3"      # 精确匹配
 qux = ">=1.0, <2.0" # 范围组合
 ```
 
+#### 命名空间解析规则
+
+每个包的身份是**命名空间 + 名字**二元组。依赖 key 的写法决定 mcpp 到哪些命名空间里找。
+
+**裸名只在三个地方解析**,按序:
+
+| # | 命名空间 | 示例 |
+|---|---|---|
+| 1 | `mcpplibs` — 默认命名空间 | `cmdline = "0.0.2"` |
+| 2 | `compat` — 第三方 C/C++ 库的包装命名空间 | `gtest = "1.15.2"` → `compat.gtest` |
+| 3 | 完全没有声明命名空间的上游包 | `opencv = "4.10.0"` |
+
+**其他命名空间一律必须写全。** 不存在按短名的全索引模糊搜索:
+
+```toml
+# ✅ 正确 —— 点式选择器
+[dependencies]
+"chriskohlhoff.asio" = "1.38.1"
+
+# ✅ 正确 —— 命名空间子表(同一组织有多个包时更推荐)
+[dependencies.chriskohlhoff]
+asio = "1.38.1"
+
+# ❌ 错误 —— 裸名永远到不了 chriskohlhoff 命名空间
+[dependencies]
+asio = "1.38.1"
+```
+
+第三种写法会明确报错,并列出搜索过的命名空间;若该短名的包存在于别处,错误信息会直接给出应当改写成的那一行。
+
+**为什么不让裸名跨所有命名空间去找?** 因为依赖解析必须可复现。全域短名搜索意味着:(a) 两个命名空间拥有同名包时,胜负由索引顺序决定;(b) **新增一个索引可能悄悄改变某个既有依赖解析到的包**。要求写出命名空间,才能让同一份 `mcpp.toml` 在每台机器上解析到相同的包。
+
+**给 xpkg 作者:** 索引描述符里的 `package.name` 必须是**完全限定名** —— 以 `package.namespace` 加一个点开头:
+
+```lua
+package = {
+    namespace = "chriskohlhoff",
+    name      = "chriskohlhoff.asio",   -- 不是 "asio"
+    ...
+}
+```
+
+包索引是以 `package.name` 字面值为键的**扁平键空间**,命名空间的区分度必须由名字本身携带 —— 否则 `mcpplibs` 的 `zlib` 与 `compat` 的 `zlib` 会撞键。写错的描述符能被正常解析,却永远装不上。`mcpp xpkg parse` 会校验这一点,请在索引 CI 里跑它。
+
 ### 2.6 `[dev-dependencies]` — 测试依赖
 
 ```toml

docs/zh/05-mcpp-toml.md

@@ -1,6 +1,6 @@
 [package]
 name        = "mcpp"
-version     = "0.0.104"
+version     = "0.0.105"
 description = "Modern C++ build & package management tool"
 license     = "Apache-2.0"
 authors     = ["mcpp-community"]