DSH Message Edit
Event-sourced message editing, rerolling, retrying, and version navigation
for DeepSeek Harness. The plugin never
rewrites history events and never touches the DSH engine internals: every
edit, reroll, or retry forks a new session version before the target turn,
while the original session is always preserved and can be switched back to at
any time.
Compatibility
- Works with DSH 0.1.0-rc.6, 0.1.0-rc.7, and newer.
- Version events (
message-edit/version) carry ignorable: true on the event
envelope: newer DSH builds skip unknown event types marked ignorable instead
of refusing the entire log, so session history stays loadable across DSH
upgrades.
Features
- Edit messages: settled user text,
assistant.reasoning thinking blocks,
and assistant.response reply text are all editable.
- Rerun: fork before the turn of the last settled assistant reply and
regenerate from the original user input.
- Retry any turn: pick any historical turn in the Timeline and re-execute it.
- Cascade policies:
truncate (default): re-execute only the target input, dropping the old
tail after that point.preserve: keep the following user inputs and re-execute them in order on
the new branch; assistant outputs and tool chains are fully regenerated.
- Version switching:
← in the session title bar undoes the current atomic
effect, → re-applies the latest direct child effect; the Timeline shows the
full known branch tree, operation time, before/after content, and the
current version.
- Timeline tab: registered on
conversation.view, order: 15, between
Trajectory (10) and Prompt Studio (20).
Installation
# npm
dsh plugin --profile web add @yunyv/dsh-message-edit
# or GitHub
dsh plugin --profile web add github:yunyv/dsh-message-edit
# or local development (link mode)
dsh plugin --profile web add -w link:/path/to/dsh-message-edit
dsh plugin is a pnpm forwarder: after add, the dsh.bundle declaration is
recognized and the plugin is adopted into the profile's dsh.profile.bundles;
restart dsh for it to take effect.
Design
Temporal composition
The plugin treats a complete turn as the atomic effect. The target turn's
turn/start, model request, tool calls, tool results, and turn/end are never
partially copied and spliced; a new version forks from a closed boundary before
that turn:
- User-message edit, Reroll, and Retry: roll back the whole target turn, then
hand the target user input to the Agent as a new turn.
- Assistant-block edit: roll back the whole target turn and construct a new
complete closed turn from the original user input plus the edited assistant
content; the original tool chain does not enter the new version. With
preserve, the following user inputs are re-executed in order, producing a
fresh tool chain.
- Each version appends an inseparable
message-edit/version effect pair:
effect records the forward effect, inverse records the restore target.
The parent chain derives composite inverses automatically; restoring is not
event deletion but switching along the inverse chain to a version that still
exists.
- Message-history transforms do not commute, so undo follows LIFO: only the
current atomic effect is undone at a time, keeping earlier effects; every
successor branch is retained and can be re-applied from the parent version.
Branching and Agent wiring
- Inside the source Agent's
runMaintenance(), take an immutable seed from
the closed boundary; before the first turn, use an empty seed.
- Append the version effect pair and an optional manual assistant turn with
local pure event constructors, then call
ctx.agents.create({ seed, meta }).
The Session validates the whole seed once before Agent construction; any
failure is structurally reverted by AgentFactory, so observers never see a
half-built Session and the Agent's turn count initializes directly from the
full history.
- Call
ctx.sessions.flush() after publishing, establishing a durability
barrier before the HTTP operation succeeds.
- Workspace attachment and child-Agent lifecycle each return an atomic
inverse; on failure they are composed in reverse order. The child input is
then queued via
child.agent.followup().
This path never touches ReactLoopAgent, AgentLoop private methods, or
apiproxy's narrowed fork RPC; branch seeds still pass through the same public
Session event contract.
Spatial composition
- Host depends only on the public
sessions, agents, sessionPersistence,
sessionQuery, workspaceRegistry, and webServer services.
- Browser composes only
slots, conversation, connection, and runtime
sessions services.
- The Timeline and title bar share a value-level Snapshot source keyed by
sessionId; the controller reactively subscribes to the current Session's
closed turns and the lineage values in the Session list, rebinding on
Session identity replacement without caching stale Session objects.
- Version navigation waits for the runtime Session list to publish the
matching ID before
ctx.sessions.open(); availability changes drive
navigation directly.
Data model
Each plugin version contains one message-edit/version event in its own
non-inherited suffix:
interface MessageEditVersionEvent {
schemaVersion: 2
effect: {
id: string
operation: 'edit' | 'reroll' | 'retry'
cascade: 'truncate' | 'preserve'
targetTurn: number
targetEventSeq: number
targetBlockIndex?: number
blockKind?: 'user' | 'assistant.reasoning' | 'assistant.response'
before?: string
after?: string
}
inverse: {
kind: 'restore-version'
sessionId: string
}
}
The session header's parentSession builds the version tree and must match
inverse.sessionId; seedLength separates the current version's own metadata
from same-named events inherited from ancestors. The Timeline derives the full
value-level projection via ctx.sessionQuery.traceSession() and
readSession(), and exports undoStack and direct redoSessionIds from the
atomic inverse chain. Legacy flat events remain readable and normalize to the
same effect pair in the projection.
UI
conversation.view
id: message-edit-timelineorder: 15label: Timeline
conversation.session.header.actions
id: message-edit-controls- undo the direct parent effect, re-apply the latest direct child effect,
effect-chain count, rerun the last reply
conversation.chat.assistant-actions
id: message-edit-assistant-actions- per-message edit / retry buttons riding the official per-message action
slot (
messageId dispatch); user messages have no such slot and are
covered by DOM injection
Components use CSS Modules and --dsw-* semantic tokens with no UI library.
Product copy is Chinese; code comments are English.
HTTP API
GET /message-edit?sessionId=<id>: readable messages, retryable turns, and
the full version tree.POST /message-edit: run edit, reroll, or retry; returns the newly
published Session ID.
Build
npm install
npm run build
Source lives in src/ (host at src/index.ts, browser at src/client/); the
build script is scripts/build.mjs on top of esbuild + lightningcss:
- Host:
src/index.ts → index.mjs (ESM, @deepseek-ai/* external)
- Browser:
src/client/index.ts → client.js + client.js.map
(window.__ModuleLoader__.load closure factory; CSS Modules are compiled by
lightningcss into a hashed class map plus idempotent <style data-plugin>
injection)
npm run typecheck (tsc --noEmit) validates types; npm run build emits
both halves.
Scope
- Never rewrites Session events; history is append-only and deep-frozen.
- Does not restore or modify workspace files, external command effects, or
existing artifacts.
- Does not modify the DSH engine, apiproxy, or official UI packages.
License
MIT — see LICENSE.
