fix(sandbox): round 5 harden spawn attribution

docs/core-data-structures/sandbox.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write docs/core-data-structures/sandbox.md
-sandbox.md: 63a80084c5b6b25d55495d2d96daef73380993f6
-sandbox.zh.md: 447552e5c80b9cf3f4dd0b684c0607843a064448
+sandbox.md: fd4861f3d89aecfd9bee8bbfcf7ac1abe15ac937
+sandbox.zh.md: 2aac7f6dfc5feeb9bf3192487a18eaaeef832e10

docs/core-data-structures/sandbox.md

@@ -139,10 +139,10 @@ interface ConfinedArgv {
 }
 ```
 
-The operator-facing local-provider key remains `runnerFailureSignatures`: an operator-configured runner must supply at least one non-empty, single-line, case-insensitive substring for its own pre-exec refusal dialect. The provider maps those entries into one rule. Consumers directly spawn `ConfinedArgv.argv`, so a missing or unexecutable runner rejects through the spawn channel rather than a stderr rule; after a process starts, child exits such as 126 or 127 remain ordinary unless the selected runner's documented fatal signature matches.
+The operator-facing local-provider key remains `runnerFailureSignatures`: an operator-configured runner must supply at least one non-empty, single-line, case-insensitive substring for its own pre-exec refusal dialect. The provider maps those entries into one rule. Consumers directly spawn `ConfinedArgv.argv`, so a missing, non-executable, or unloadable runner — including a script whose shebang interpreter is unavailable — rejects through the spawn channel rather than a stderr rule; after a process starts, child exits such as 126 or 127 remain ordinary unless the selected runner's documented fatal signature matches.
 
 ## Provider and fail-closed errors
 
-`ctx.sandbox.confine(argv, policy)` returns a `ConfinedArgv` or throws `SandboxUnavailableError` with code `SANDBOX_UNAVAILABLE` when no usable backend exists. A direct spawn rejection of the returned argv proves the confined launch never started and carries the same infrastructure meaning with the original error as detail. After a process starts, a matching structured rule identifies a runner refusal. Silent unconfined passthrough is never legal for a confined policy.
+`ctx.sandbox.confine(argv, policy)` returns a `ConfinedArgv` or throws `SandboxUnavailableError` with code `SANDBOX_UNAVAILABLE` when no usable backend exists. Any direct spawn rejection of the returned argv proves the confined launch never started, but only an executable-class error with Node spawn provenance for provider argv[0] after the caller-owned workdir is independently verified usable carries infrastructure meaning and the original error as detail. Invalid or unusable workdirs, resource failures, unrelated syscalls, and unstructured rejections retain the consumer's ordinary command-start semantics. After a process starts, a matching structured rule identifies a runner refusal. Silent unconfined passthrough is never legal for a confined policy.
 
 Provider probing arbitrates between multiple candidates and is cached for the provider lifetime. A platform with one candidate may select it directly; execution-time refusal retains the safety property. The local provider reports bwrap and Seatbelt as full and preserves the Landlock launcher's full/partial kernel verdict.

docs/core-data-structures/sandbox.zh.md

@@ -139,10 +139,10 @@ interface ConfinedArgv {
 }
 ```
 
-面向运维人员的本地提供方配置键仍为 `runnerFailureSignatures`：运维人员配置的 runner 必须为自身的 pre-exec 拒绝方言提供至少一个非空、单行、不区分大小写的子串。提供方会将这些条目映射到一条规则。消费方直接 spawn `ConfinedArgv.argv`，因此 runner 缺失或不可执行时会在 spawn 通道遭拒，而不是由 stderr 规则判定；进程启动后，126 或 127 等子进程退出码仍按普通结果处理，除非匹配所选 runner 文档所定义的致命签名。
+面向运维人员的本地提供方配置键仍为 `runnerFailureSignatures`：运维人员配置的 runner 必须为自身的 pre-exec 拒绝方言提供至少一个非空、单行、不区分大小写的子串。提供方会将这些条目映射到一条规则。消费方直接 spawn `ConfinedArgv.argv`，因此 runner 缺失、不可执行或无法加载（包括脚本的 shebang 解释器不可用）时会在 spawn 通道遭拒，而不是由 stderr 规则判定；进程启动后，126 或 127 等子进程退出码仍按普通结果处理，除非匹配所选 runner 文档所定义的致命签名。
 
 ## 提供方与 fail-closed 错误
 
-`ctx.sandbox.confine(argv, policy)` 返回一个 `ConfinedArgv`，或在没有可用后端时抛出 `SandboxUnavailableError`（错误码 `SANDBOX_UNAVAILABLE`）。直接 spawn 所返回的 argv 时若遭拒，即可证明受限启动从未开始；该拒绝具有相同的基础设施含义，并以原始错误作为详细信息。进程启动后，匹配到的结构化规则标识 runner 拒绝。对于受限策略，静默的无隔离透传永远不合法。
+`ctx.sandbox.confine(argv, policy)` 返回一个 `ConfinedArgv`，或在没有可用后端时抛出 `SandboxUnavailableError`（错误码 `SANDBOX_UNAVAILABLE`）。直接 spawn 所返回的 argv 时，任何拒绝都能证明受限启动从未开始；但只有在调用方拥有的 workdir 经独立验证可用，且错误属于带有 Node 为提供方 argv[0] 报告的 spawn 来源信息的可执行文件类错误时，该拒绝才具有基础设施含义，并以原始错误作为详细信息。无效或不可用的 workdir、资源失败、无关 syscall 和无结构拒绝仍保留消费方的普通命令启动语义。进程启动后，匹配到的结构化规则标识 runner 拒绝。对于受限策略，静默的无隔离透传永远不合法。
 
 提供方探测在多个候选后端之间仲裁，结果在提供方生命周期内缓存。只有一个候选后端的平台可以直接选定它；执行时拒绝仍保留安全属性。本地提供方将 bwrap 和 Seatbelt 报告为 full，并保留 Landlock 启动器的 full/partial 内核裁定。