@andrewhmir/dsh-btw — ephemeral /btw side questions for the DSH Web GUI
An unofficial community plugin for DeepSeek Harness
(DSH). It adds one gesture to the Web GUI composer:
/btw how does the compaction checkpoint interact with the surface?
The answer streams into an overlay over the app. Dismissing it leaves no
trace in the session: the question and answer are never appended to the
transcript, never rendered as chat rows, and never become part of what the model
sees on the next turn.
It is the inverse of a subagent: a subagent gets the full tool surface and an
empty context; /btw gets the full conversation context and no tools.
What /btw does
| property | behavior |
|---|
| invocation | /btw <question> typed in the composer, mid-session; also selectable from the / menu |
| context | the full committed conversation of the current session |
| tools | none — the request carries no tool schemas and no tool history |
| answer | streamed into an overlay over the app frame |
| dismissal | Space, Enter, or Escape (also the close button / backdrop) |
| persistence | none — the exchange never enters session history |
| concurrency | works while the main turn is streaming and never interrupts it |
| shape | single-shot; no follow-up turns |
| model | the session's routed provider/model/reasoning effort |
| cost | one tool-less call whose message prefix is the parent request's prefix, so the provider's prompt cache is reused |
Requirements
- DSH
>= 0.2.0-rc.2 with the Web GUI (dsh web).
- Node.js 22 or newer only for the verification scripts; the plugin itself runs
inside the harness process.
Install
The package is a DSH bundle: it declares dsh.bundle.patch and one
client+host plugin row (id: btw). Install it into the profile you run, then
restart dsh web.
From a plugin market
Enable DSH's custom plugin market, add a community index that lists this package
(the repository carries the dsh-plugin GitHub topic so indexes can discover
it), and install @andrewhmir/dsh-btw from the Discover tab.
With the agent
plugin_manager install_bundle target: @andrewhmir/dsh-btw@0.1.2
From a local checkout
plugin_manager install_bundle target: /absolute/path/to/dsh-btw
After installing
Restart dsh web. The running process holds its pre-install module graph;
a restart loads the new host half. Then confirm the composition:
dsh --profile web --dump-config
Expected: exit code 0 and a row id: btw / name: @andrewhmir/dsh-btw with no
not found, unknown key, or cannot resolve lines.
After editing only client.js, the harness's client HMR picks the rebuilt file
up on save; host-half edits need a restart.
How it works
ui-commands claims slash commands that exist in the session's host
command catalog. /btw deliberately does not register such a command: a host
command's result is durably logged (command/run / command/done) and would
enter the session history.- Instead, the plugin's client half registers its own
'/' input-trigger
source. During composer adjudication it claims /btw <question> before any
host command runs, opens the overlay, and calls the plugin's own loopback
route POST /btw/ask.
- The host half resolves the live agent for the session, snapshots the exact
model-visible history with
Session.deriveMessages(), appends one frozen user
message carrying the side question, and runs a single ctx.llm.stream() call
with no tools, no tool history, and no separate system prompt. Because the
message list is the parent request's prefix plus one trailing message, the
provider's prompt cache is reused.
- The answer streams back as newline-delimited JSON, renders Markdown through
the shell's shared
MarkdownText component (plain-text fallback if an older
shell does not seed it), and is shown in a shell.overlay panel.
Space/Enter/Escape abort the request and close it.
- A snapshot taken mid-turn can end with an assistant tool call whose
tool/result is not committed yet. The host trims that trailing unresolved
step before replaying the history, so /btw answers with the conversation as
of the last completed tool step instead of the provider rejecting the request
("tool calls need immediate results").
- Nothing in this path calls
session.append, the command registry, the agent
loop, or the inbox — that is what makes the exchange ephemeral.
Private by design
The ephemerality is a contract, not a rendering choice:
- the question and answer are never written to the session log, so they are not
in the transcript, the token meter's session history, or any export;
- the host route never touches
session.append, the command registry, the agent
loop, or the inbox;
- the only durable effect is provider billing for one call.
It is verified against real session logs: test/e2e/ephemerality-check.mjs
decodes every session.v*.jsonl.zstd in a test home and fails if the question or
any part of the answer appears in a persisted event. A control run proves the
scanner detects text that is legitimately persisted. Results for both supported
harness versions are recorded in docs/VERIFICATION.md.
Configure
The plugin row accepts two optional values; both have safe defaults and are read
without a Config schema:
- insert:
- id: btw
name: '@andrewhmir/dsh-btw'
config:
maxTokens: 1200 # completion cap for one side answer (default 1200)
timeoutMs: 120000 # hard deadline for one side call (default 120000)
Questions are capped at 4000 characters; the request body is capped at 32 KiB.
Known limitations
- In-flight partial assistant text is not included. The snapshot reads the
committed session surface; while the main turn is streaming, the current
assistant message is not committed yet.
/btw sees the conversation as of the
last committed event.
- Not visible in session-log cost dashboards. Ephemeral calls leave no
session-log trace; provider billing is the source of truth for them.
- Web GUI only. The host route is generic, but the invocation and overlay are
client-side Web features.
- English overlay copy. Display metadata ships in English and Chinese;
in-overlay strings are English in this version.
- A future host
btw command would shadow this plugin. The host catalog is
adjudicated before the plugin's source; if a future harness version ships a
host command with the same name, /btw would execute that command instead.
- Single-shot. There is no follow-up turn inside the overlay.
Compatibility
engines.dsh declares >=0.2.0-rc.2. Both tags were verified on a clean-room
install containing only the official bundles plus this plugin:
| Harness | Result |
|---|
0.2.0-rc.2 (npm latest) | overlay + streamed answer, uppercase /BTW, Markdown, Escape/Space/Enter dismissal, warm cache |
0.2.1-rc.2 (npm next) | the above, plus mid-stream concurrency (4/4 answers during a tool call) and strict ephemerality |
See docs/VERIFICATION.md for the measurements and the
exact commands.
Verify
From this directory:
node --test "test/*.test.mjs"
node tools/build-client.mjs --check
node --check client.js
The clean-room and browser harness lives in test/e2e/ and is documented there.
It is not shipped in the published package:
clean-room.ps1 builds a fresh DSH home with only the official bundles plus
this plugin, seeds the workspace state, composes, boots, and prints the URL;first-run.mjs dismisses the first-run preview notice and proves the composer
accepts text;cdp-e2e.mjs drives the real GUI over the DevTools protocol (probe, full,
dismiss-keys, mid-stream);ephemerality-check.mjs asserts that no exchange reached a session log.
Development
node tools/build-client.mjs # regenerate client.js from src/client/*.mjs
node tools/build-client.mjs --check # fail when client.js is stale
node --test "test/*.test.mjs"
client.js is a generated classic script that registers itself with the
harness's module loader under the package name. Source modules under src/client/
are plain ESM with relative .mjs imports only; the host half lives in src/host/
and is injected with the harness services (webServer, llm, agents).
Independence and license
This is an unofficial community plugin, not affiliated with DeepSeek. It is an
independent implementation of the /btw idea and does not reuse code from the
other community packages with similar names (dsh-btw@0.0.3 and
@michengai/dsh-btw). Upstream DSH does not accept external pull requests at
the moment, so distribution is a standalone package; the repository carries the
dsh-plugin topic so community plugin indexes can discover it.
MIT. See LICENSE.
