fix(config): trust the invoking project, and stop leaking what it must not decide

Review found five real defects in the configuration-source work, all confirmed
against the code rather than argued:

1. The note claimed --config outranks settings.yaml. It does not: the settings
   seam registers a plugin's cordis entry config as the `base` layer and the
   user section layers over it, and the seam cannot tell a shipped value from a
   --config one. The note now states shipped reality and names --config-replace
   as the lever for a deployment that must win. Separately, a literal `apiKey`
   in settings outranked both the environment and .credentials.yaml — the field
   is removed, so configuration carries a reference and nothing else.
2. DEEPSEEK_SEARCH_BASE_URL was functionally deleted: the shipped inline went
   away without the provider learning to read it. It now resolves from the
   environment snapshot, as the README always claimed.
3. The bootstrap deny list missed the interpreter start-up hooks. BASH_ENV is
   the sharpest: `bash -c` sources it on every bash tool call, so a project
   .env could run a file of its choosing before every command. The list now
   covers BASH_ENV and its per-language siblings, the Git hook commands, and
   the remaining preload and CA variables, organised by what a variable does
   rather than which runtime owns it.
4. YAML parse errors quoted the offending source line — which in a credentials
   document is the secret — into boot stderr and the watcher's logger. Only the
   error code and position are reported now, in credentials-local and
   settings-local alike, pinned by a test that asserts the secret is absent.
5. 0600 governed only files the harness wrote. A hand-created 0644 document was
   read normally. POSIX now checks the mode before reading contents, at boot
   and on every reload; Windows has no mode to inspect and is skipped rather
   than faked.

The project a session is launched in is trusted by default, with no prompt and
no stored trust record: it may supply its own endpoint, ordinary variables, and
a key ranked below the managed store. Trust stops at the harness itself — a
discovered file still cannot set DSH_PERMISSION_MODE, PATH, BASH_ENV, or the
rest, because those take effect with no user action, before any turn, outside
the permission policy and the sandbox.

packages/util/environment/README.zh.md

@@ -7,7 +7,7 @@
 | 层 | 来源 id | 它是什么 |
 |---|---|---|
 | 继承的进程环境 | `process` | 启动 shell、CI 任务或容器传入的东西——本次运行的明确意图 |
-| `<invocation cwd>/.env` | `project-env` | 项目目录里恰好有的东西；在该工作区里工作的模型可以写它 |
+| `<invocation cwd>/.env` | `project-env` | harness 被启动于其中的项目；产品信任它配置自己的 agent |
 | `$DSH_HOME/.env` | `user-env` | 用户自己的机器级默认值 |
 
 这些值同样会进入 `process.env`——用户自己的 `--config` 树和第三方库要读它——但那份压平的视图不是 harness 解析任何值的依据。
@@ -16,14 +16,14 @@
 
 `get(name)` 按可信度从高到低搜索所有层。`getFrom(name, sources)` 只搜索调用方信任的层。
 
-**省略某一层是拒绝，不是降级。** base URL 决定已解析的 API key 被发往何处，因此 LLM 适配器请求的是 `['process', 'user-env']`：后续任何重新排序都无法让项目文件重定向凭据，因为那一层根本不会被查询。
+**省略某一层是拒绝，不是降级**——绝不能接受某一层的调用方直接不把它列进去，后续任何重新排序都无法让它回来。provider 适配器三层全列，因为产品信任它所运行的项目；该机制是为那些「并非如此」的决策准备的。
 
 ```ts
 import type { Context } from 'cordis'
 import { environmentOf } from '@deepseek-ai/dsh-environment'
 
 declare const ctx: Context
-const endpoint = environmentOf(ctx).getFrom('DEEPSEEK_BASE_URL', ['process', 'user-env'])?.value
+const endpoint = environmentOf(ctx).getFrom('DEEPSEEK_BASE_URL', ['process', 'project-env', 'user-env'])?.value
 ```
 
 当产品 CLI（命令行界面）启动了这棵树时，`environmentOf(ctx)` 返回启动器的快照；否则返回只含继承环境的那一层。该回退并不削弱规则：SDK 宿主或裸 `cordis.yml` 从未发现过任何文件，因此它拥有的一切确实就是它被启动时的环境。
@@ -32,11 +32,13 @@ const endpoint = environmentOf(ctx).getFrom('DEEPSEEK_BASE_URL', ['process', 'us
 
 `isBootstrapOnly(name)` 给出只有继承环境才能设置的变量。启动器一旦发现某个 `.env` 声明了其中之一，就会在应用任何内容之前拒绝启动。
 
-bootstrap 变量决定**进程如何启动**（`PATH`、`SHELL`、`NODE_OPTIONS`、`NODE_PATH`、`LD_PRELOAD`、`LD_LIBRARY_PATH`、`DYLD_*`）、**代码或模型可见的指令从哪里加载**（整个 `DSH_*` 命名空间、`HOME`、`USERPROFILE`、`XDG_*`），或者**网络如何抵达与信任**（`HTTP_PROXY`、`HTTPS_PROXY`、`ALL_PROXY`、`NO_PROXY`、`SSL_CERT_FILE`、`SSL_CERT_DIR`、`NODE_EXTRA_CA_CERTS`）。匹配不区分大小写，因此 `https_proxy` 不是绕过手段。
+信任一个项目配置 agent 的工作，不等于让它改变 harness 本身。bootstrap 变量决定**进程如何启动**（`PATH`、`SHELL`、`NODE_OPTIONS`、`LD_PRELOAD`、`DYLD_*`）、**运行时在执行被要求运行的程序之前先执行哪些代码**（`BASH_ENV` 及其各语言同类——`PERL5OPT`、`PYTHONSTARTUP`、`RUBYOPT`、`JAVA_TOOL_OPTIONS`——以及 Git 的钩子命令）、**模型可见的指令从哪里加载**（整个 `DSH_*` 命名空间、`HOME`、`XDG_*`），或者**网络如何抵达与信任**（proxy 与 CA 变量）。匹配不区分大小写，因此 `https_proxy` 不是绕过手段。
+
+这些变量无需任何用户动作、在任何一轮开始之前、且在权限策略与沙箱之外就生效：`DSH_PERMISSION_MODE` 会关掉让「信任项目」有意义的那道审批，而 `BASH_ENV` 会在 bash 工具发出的每一次 `bash -c` 上执行项目指定的文件。
 
 整个 `DSH_*` 命名空间被拒绝，而不是只拒绝一份经过审查的子集：harness 自己的开关——权限模式、agents home、内置 skill（技能）根目录——恰恰是敌意项目最想要的，而后来新增的开关不能因为忘记登记就变得可设置。
 
 ## Known Limitations and Deferred Work
 
-- **快照不是子进程边界**：每一层同样会被物化进 `process.env`，因此普通的项目变量仍会按 [`dsh-subprocess`](../../subprocess/subprocess/README.md) 的清洗规则抵达子进程。bootstrap 变量完全不能来自文件，但项目 `.env` 仍可以为 agent 运行的工具设置诸如 `GIT_SSH_COMMAND` 之类的变量。
+- **快照不是子进程边界**：每一层同样会被物化进 `process.env`，因此项目里的普通变量会按 [`dsh-subprocess`](../../subprocess/subprocess/README.md) 的清洗规则抵达子进程。这对普通变量是有意为之；会滥用这一点的代码加载钩子改为在加载时拒绝，新的运行时钩子出现时该扩展的是那份拒绝清单。
 - **没有按工作区划分的层**：项目层是*调用*目录，在启动时固定。之后在 Web UI 中选择的工作区不贡献任何内容，这是刻意的：跟随它等于让模型自己的工作区在会话中途改变 harness 的环境。