lembas -l / --local: everything in the project, nothing written elsewhere

Config, data and state are rooted at <project>/.agent/local/lembas (or
.lembas/), kept out of git; a local directory the repository carries is
refused. The user's logins and connections.yaml are read, never written; the
user's config.yaml is not read. The TUI is started with TMPDIR inside it (the
compiled binary unpacks its native library there) and OpenTUI's cache goes
there too; the agent's commands keep the user's TMPDIR.

An instance serves models, chat, speech and the balance only: the link,
/remote, the service and the hub are off, deletes are not sent, and the server
library, search, fetch, embeddings and personalization are not used.
Self-update and uninstall are refused. hardline_disable is ignored, and tools
treat the local directory as outside the project.

The smoke test runs a whole local session in the compiled binary and checks
that HOME, the XDG directories and TMPDIR gained nothing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/settings.ts

@@ -5,6 +5,7 @@ import { mkdirSync, writeFileSync } from "node:fs"
 import { assertProjectFile } from "./project/safe.ts"
 import { dirname, join } from "node:path"
 import { findSetting, globalConfigFile, legacyInstructionFiles, parseValue, readRaw, SettingError, SETTINGS, show, sourceOf, writeKey, type Entry, type Scope, type SettingDef } from "./config/settings.ts"
+import { isLocal } from "./config/paths.ts"
 
 export interface SettingsHost {
   /** The project's config.yaml, when the project is trusted (else project scope is refused). */
@@ -87,7 +88,7 @@ export class Settings {
     }
     if (!def.reload) this.host.apply(key, value)
 
-    const where = scope === "session" ? "for this session" : elsewhere ? "for your account" : scope === "global" ? "in the global config" : "in this project's config"
+    const where = scope === "session" ? "for this session" : elsewhere ? "for your account" : scope === "global" ? (isLocal() ? "in local mode's config" : "in the global config") : "in this project's config"
     let message = `${key} = ${show(value)} ${where}`
     if (def.reload) message += "; it takes effect from the next start (/reload)"
     for (const n of notes) message += `; ${n}`