dsh-acp-replay

A community ACP bridge for DeepSeek Harness that answers session/load, so a client can rebuild a session transcript after its own restart.

Status: prototype. It works end to end on dsh 0.1.5-rc.1, but it is a vendored fork of @deepseek-ai/dsh-acp and needs a rebase whenever that package changes.

Published on npm as dsh-acp-replay. Its version is independent of the harness version it targets, which peerDependencies states. (0.1.5-rc.1 was published with an incomplete file list, so it fails to load; it is deprecated. Use 0.1.0 or newer.)

Why this exists

dsh-acp is an automation-only bridge: its initialize advertises sessionCapabilities: { close, list, resume } and no loadSession, and session/resume restores a session without replaying its updates. ACP defines session/load as the call where the agent "streams the entire conversation history back to the client via notifications", and clients that treat the agent as the durable transcript authority — Paseo, for one — call exactly that method to rebuild a timeline after restarting.

Without it, that model of client shows an empty conversation next to an agent that still remembers everything, because the harness keeps the transcript and the client has no way to read it. This bridge closes that gap; the discussion tracking the missing upstream feature is deepseek-ai/deepseek-harness#6324.

What it adds

Two changes over @deepseek-ai/dsh-acp@0.1.5-rc.1:

• initialize advertises loadSession: true.
• session/load is implemented: it opens the stored session with a read-only persistence handle (ctx.sessionPersistence.open(id, 'read')), resumes the session exactly as session/resume does, then replays the snapshot through the existing update mapping in src/updates.ts before returning.

src/replay.ts maps stored events to protocol updates:

Stored event	ACP update
user/message with source.kind === 'user'	user_message_chunk
assistant/message	agent_thought_chunk, agent_message_chunk, usage_update
tool/call	tool_call
tool/result	tool_call_update

Injected context (the runtime snapshot, skill lists, file-change notices) shares the user/message event type but is not something a user said, so it stays off the wire.

Fail-fast guard

The bridge needs the persistence handle API (ctx.sessionPersistence.open(id, 'read'), then read(0)) that 0.1.5-rc.1 introduced; 0.1.2-rc.1 read logs with load/inspect on the service instead. When the mounted harness does not offer what the bridge calls, src/compat.ts refuses to mount and prints the missing requirement, the alternative bridge, and this repository:

dsh-acp-replay cannot serve session/load in this harness (harness 0.1.6):
  - needs ctx.sessionPersistence.open(), but the mounted sessionPersistence service exposes inspect, list, load, stat
This plugin vendors @deepseek-ai/dsh-acp@0.1.5-rc.1 and needs the persistence handle API it introduced.
Use the shipped bridge instead ("dsh --profile acp"), or update this plugin for the installed harness.
https://github.com/zheng1/dsh-acp-replay

Run node test/selfcheck.mjs after a harness upgrade to get that answer without a full client.

Use it

The bridge replaces the shipped acp row in a profile. Two ways:

Install into an existing profile. Add the package to the profile and append to its cordis.patch.yml:

Published on npm as dsh-acp-replay:

dsh plugin --profile acp-replay add dsh-acp-replay   # installs it into that profile

The same package also works installed globally (npm install -g dsh-acp-replay) or copied from a checkout (put lib/ and package.json in $DSH_HOME/profiles/node_modules/dsh-acp-replay/).

- id: acp
  disabled: true

- insert:
    - id: acp-replay
      name: 'dsh-acp-replay'
      inject: [acpAppStartup]
      config:
        provider: deepseek-official
        model: deepseek-flash

Then point the client at dsh --profile acp-replay instead of dsh --profile acp. In Paseo that is the provider's command:

{
  "agents": {
    "providers": {
      "dsh": {
        "extends": "acp",
        "label": "DeepSeek Harness",
        "command": ["dsh", "--profile", "acp-replay"]
      }
    }
  }
}

Or use it as a bundle. The package declares dsh.bundle.patch, so adding dsh-acp-replay to a profile's dsh.profile.bundles composes the same rows.

Build

npm install --legacy-peer-deps   # the 0.1.5 peer graph has an rc.1/rc.2 skew
npm run build                    # tsc -> lib/
npm test                         # guard behaviour (node:test)

Verified

Against dsh 0.1.5-rc.1, a scratch DSH_HOME, and a real API key:

• initialize reports loadSession: true.
• A session with two prompts runs normally through the bridge (session/new, session/prompt, session/close).
• A new process calling session/load for that session id receives user_message_chunk ×2 and agent_message_chunk ×2 carrying the original prompts and answers, plus usage_update ×2.

test/replay-check.mjs runs both phases (record then load ); test/selfcheck.mjs only performs initialize and reports whether loadSession is advertised.

End to end through a client (Paseo 0.7.2 daemon, dsh 0.1.5-rc.1, two DSH providers on one daemon so only the bridge differs). Each agent ran one prompt, then the daemon was restarted — the event that used to erase the visible conversation:

Provider	Before restart	After restart
dsh-replay (this bridge, advertises loadSession)	user prompt, assistant answer, reasoning row	all three rows restored
dsh (shipped bridge, no loadSession)	user prompt, assistant answer	No activity to display.

Paseo's ACP adapter takes the loadSession branch only when the agent advertises the capability, primes its timeline from streamHistory(), and needed no change for this to work.

Not verified / known limits

• Tool-call replay is mapped but not exercised by the test above.
• An older host (dsh 0.1.2-rc.1) exposes a different persistence API (load/inspect instead of open/read), so this fork targets 0.1.5-rc.1 and newer only.
• Replayed history is delivered before session/load returns, one notification at a time; a very long session makes that call proportionally long.
• The profile's own help text still reads --profile acp (it comes from the bundled dsh-acp-app command provider, not from this package).

License

MIT, matching the upstream package it vendors. src/*.ts except src/replay.ts are copied from @deepseek-ai/dsh-acp at tag dsh-v0.1.5-rc.1; the additions are the loadSession capability, the loadSession handler in src/index.ts, and src/replay.ts.