deepseek-harness/packages/ui/app-boot/README.md

@deepseek-ai/dsh-app-boot

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Shared boot glue for the app bins (dsh, dsh-cli-demo, dsh-acp-demo): each bin is a thin self-executing composition over these helpers, parameterized by its diagnostic prefix, so the loader-failure lore lives once — under the per-file coverage gate — instead of drifting between published artifacts.

Export	Role
resolveConfigPath(path, snapshotMode, cwd?)	Absolute config path; snapshotMode === 'replay' swaps a cordis.yml/.yaml basename for its sibling cordis.snapshot.yml
loadEnv(binName, dir?, warn?)	Load the gitignored .env (Node process.loadEnvFile); absent file is fine, an unloadable one warns a single labelled line (default: stderr)
installFailLoud(binName, proc?)	Turn a post-boot() unhandled Loader rejection into one labelled stderr line + exit(1); returns the uninstaller (for tests)
assertEntriesLoaded(ctx, binName)	Throw when a settled tree holds an enabled entry with no fiber, reporting every unresolved plugin name as a Cordis startup failure
assertEntriesActive(ctx, binName)	Throw when a settled enabled fiber is not ACTIVE, including missing injected services for PENDING entries
loadPersonalPatches(binName, dir?)	Parse the optional config.yaml in the Harness home (default resolveDshHome(): $DSH_HOME, else ~/.dsh) — a top-level YAML array of include PatchOptions (id-targeted config overrides, insert lists, !!js allowed); absent file → undefined, an unreadable/unparsable/non-array file throws
loadOverlayPatches(binName, file)	Parse a required patch-list file with the same shape as personal config; read or parse failures throw a labelled error
boot(binName, absoluteConfigPath, patches?, prepare?)	Create the root context, install Loader, run optional host preparation before config-tree entries mount (prepare may use Loader and provide launcher-owned context slots such as MAIN_SESSION_ID_KEY), then mount and await the include tree, assert entries loaded and ACTIVE, and return the root context
addHarnessSourceSection(ctx, sourceRoot)	Add a global harness:source prompt section (ordered just after the harness identity, before the persona) telling the agent the on-disk path to its own source checkout; a no-op returning undefined when the booted tree has no systemPrompt service. The section is registered against that service's fiber, so a dev HMR reload of the system prompt drops it until the next boot
HARNESS_SOURCE_SECTION	The 'harness:source' section name addHarnessSourceSection registers under

Two failure classes the guards handle: loader.await() swallows init rejections (Promise.allSettled) — Node still exits non-zero on the resulting unhandled rejection, and installFailLoud replaces the noisy dump with one labelled line and a guaranteed exit(1); a failed plugin import is only logged by the Loader (the process would otherwise exit 0 on a usable config typo), leaving a fiber-less entry that assertEntriesLoaded turns into a boot() rejection naming every failed plugin.

Bare plugin specifiers in a config (@deepseek-ai/dsh-*, npm packages) resolve through the Cordis Loader's internal module loader. Repository bins install Loader's optional node-addon-require-builtin peer; external callers must supply it or install plugins where plain Node import resolution can find them. Relative specifiers resolve against the config directory without the native helper. The dsh source launcher additionally maps manifest-declared workspace packages to their TypeScript source; its configuration gate requires every TUI/Web bare plugin to appear in the resolver manifest's dependencies. The bins' subprocess smokes exercise the internal-loader path, while this package's unit suite drives boot() in-process against configs with relative specifiers.

This package carries no loader hooks and no dev-mode surface. The dsh app owns its Node source-launch hook and consumes these helpers for the boot sequence; built consumers continue to use plain Node package resolution.

Personal config

A developer's machine-local preferences live outside every repository in the Harness home (default ~/.dsh, overridable via $DSH_HOME; the single root resolveDshHome resolves), consumed by the official dsh surfaces (apps/cli); the demo bins boot their committed trees verbatim. Two optional files:

• .env — the credential store of dsh-credentials-local, read by that provider alone. No surface hoists it into process.env: doing so would make every stored key look like a read-only launch override on the next run, blocking rotation from the TUI and the web page. The environment layers are the ambient one and the invoking directory's .env (loaded by the bin; process.loadEnvFile never overrides), and a composition without the credential provider keeps resolving keys from those alone.
• config.yaml — loader overlay patches applied over the shipped default config, with the same semantics as the shipped surface overlays: an id-targeted patch replaces the named entry's whole config (restate unchanged fields), insert adds entries, and !!js expressions interpolate at mount. A patch naming an entry id absent from the booted tree is a silent no-op. An empty or comments-only file throws (it parses to nothing, not to a list); disable the overlay with [] or by deleting the file.

Subprocess test launchers point DSH_HOME at an isolated per-test directory so a developer's personal overlay can never leak into fixtures.

Model Experience

Indirectly, through the plugin tree it loads, which determines the prompts, schemas, messages, and model adapter in the resulting application; the one export that contributes model-visible text, addHarnessSourceSection, does so only when a consumer calls it after boot.

KV Cache effect

No direct invalidation from boot(); a consumer that calls addHarnessSourceSection places one short line near the system prompt's head, before per-request content, so it does not invalidate the cache across turns, and any other request-prefix change is owned by the named consumer.

Known Limitations and Deferred Work

• Bare package specifiers depend on Loader internals — production bins need Loader's optional native helper; an in-process caller without it must use resolvable relative/file specifiers or provide its own module-resolution hook.
• Snapshot replay swapping is basename-specific — only a config ending in cordis.yml or cordis.yaml maps to the sibling cordis.snapshot.yml; custom config names require caller-managed selection.
• Environment loading is cwd-scoped and optional — the helper loads one .env file and warns on failure; it does not search parents, merge profiles, or validate required variables.
• Personal config is patch-shaped — an id-targeted patch replaces the entry's whole config rather than deep-merging, so a personal override restates the base fields it keeps.