feat(config)!: one ordering for configuration sources, and a bootstrap deny rule

$DSH_HOME/.env had just become an ordinary environment layer, which left the
harness resolving user-facing values from a flattened process.env that could
no longer say where a value came from. A key stored through the web page
stayed shadowed by an older key in the user's own .env. An endpoint could be
redirected by the project: the invoking directory's .env is materialized like
every other layer, and a base URL decides where a resolved API key is sent, so
a DEEPSEEK_BASE_URL written into a model-editable workspace would send the
user's credential — and the prompts carrying their code — to whatever host
that file named.

Give every user-facing value one ordering, with four kinds of source:

  explicit for this run     per-operation override, CLI argument
  > authored by deployment  --config / --config-replace
  > this launch's shell     inherited process environment
  > product-managed store   settings.yaml, .credentials.yaml
  > discovered file         $DSH_HOME/.env
  > defaults                schema default, shipped base, public default

The domains differ only in which tiers exist. The earlier split — credentials
ranking the environment over the managed file while settings ranked over the
environment — was inconsistent: the distinguishing fact is who authored the
source, not the domain.

packages/util/environment owns an immutable snapshot with per-layer
provenance. getFrom(name, sources) searches only the layers a caller names,
and omitting one is a refusal rather than a demotion: the adapters ask for
['process', 'user-env'], so no reordering can let a project file back into a
decision it was excluded from.

isBootstrapOnly rejects, before anything is materialized, any .env setting a
variable that governs how a process launches (PATH, SHELL, NODE_OPTIONS,
LD_PRELOAD), where code or model-visible instructions load from (the whole
DSH_* namespace, HOME, XDG_*), or how the network is reached (proxy and CA
variables). The namespace is denied wholesale so a switch added later cannot
become settable by being forgotten, and there is no opt-out.

verify-config-source-ownership keeps both rules: no unregistered process.env
read under packages/*/*/src (26 allowlisted with reasons), and no apiKey,
baseURL, or headers inlined from the environment in shipped Cordis config —
removing those inlines is what makes the deployment tier meaningful.

packages/llm/llm-deepseek/tests/adapter.spec.ts

@@ -1,5 +1,6 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { Context } from 'cordis'
+import { createEnvironmentSnapshot } from '@deepseek-ai/dsh-environment'
 import LlmService, { createUserMessage,
   CONTEXT_WINDOW_EXCEEDED_CODE,
   errorChain,
@@ -12,7 +13,7 @@ import LlmService, { createUserMessage,
 import { MAX_TIMER_DELAY_MS } from '@deepseek-ai/dsh-timeout'
 import { SessionId } from '@deepseek-ai/dsh-session'
 import * as LlmDeepSeek from '@deepseek-ai/dsh-llm-deepseek'
-import { DeepSeekAdapter, resolveAdapterOptions } from '@deepseek-ai/dsh-llm-deepseek'
+import { DeepSeekAdapter, PUBLIC_BASE_URL, resolveAdapterOptions } from '@deepseek-ai/dsh-llm-deepseek'
 import { httpErrorCode } from '../src/adapter.ts'
 import { assemble } from './assemble.ts'
 import { closeMockServers, mockServer, textEvents } from './mock-server.ts'
@@ -906,6 +907,25 @@ describe('plugin registration and config', () => {
     expect(server.requests).toHaveLength(1)
   })
 
+
+  it('takes DEEPSEEK_BASE_URL from the launching shell or the user .env, never from the project', () => {
+    const trusted = createEnvironmentSnapshot([
+      { source: 'user-env', path: '/home/.dsh/.env', values: { DEEPSEEK_BASE_URL: 'https://user.example' } },
+    ])
+    expect(resolveAdapterOptions({}, trusted).baseURL).toBe('https://user.example')
+    // A base URL decides where the resolved API key is sent, so a file inside
+    // a model-writable workspace must not be able to redirect it.
+    const project = createEnvironmentSnapshot([
+      { source: 'project-env', path: '/work/.env', values: { DEEPSEEK_BASE_URL: 'https://attacker.example' } },
+    ])
+    expect(resolveAdapterOptions({}, project).baseURL).toBe(PUBLIC_BASE_URL)
+    // An explicitly configured endpoint outranks every environment layer, so a
+    // stale shell value cannot rewrite a deployment's own gateway.
+    const shell = createEnvironmentSnapshot([
+      { source: 'process', values: { DEEPSEEK_BASE_URL: 'https://stale.example' } },
+    ])
+    expect(resolveAdapterOptions({ baseURL: 'https://gateway.internal' }, shell).baseURL).toBe('https://gateway.internal')
+  })
   it('defaults to the public base URL without config or env', async () => {
     vi.stubEnv('DEEPSEEK_API_KEY', 'k')
     vi.stubEnv('DEEPSEEK_BASE_URL', undefined)