dsh-last-turn-delete

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DeepSeek Harness (DSH) plugin bundle: a trash-can button on the newest deletable item of a conversation — the last user message, or a failed /compact card. A click (confirmed in a small bubble) soft-deletes it, then the button walks back to the previous item until a real compact boundary or nothing is left.

Why

Long agentic sessions pile up turns you no longer want the model to remember — and failed /compact cards that sit in the way. DSH's session log is append-only by design, so there is no built-in "remove this turn"; this plugin deletes on the model-visible surface using the same mechanism compaction uses, leaving your durable log untouched.

What "delete" means

• User message + its whole reply tail are shadowed from the model surface by one replacement event — they stop entering the context of every later request. Original events stay on disk; the turn is dimmed in place ("soft delete", nothing is lost).
• Failed /compact cards never compacted anything, so they are not compact boundaries — they can be deleted too. Deleting one records the command id in a small private sidecar (the dsh_last_turn_delete storage domain) and the chain simply continues past it. Successful compactions remain real boundaries: everything they covered (already off the model surface) is not deletable.
• The button only appears once the agent has finished replying (the host reports running); it is hidden mid-stream.

Install

Requires pnpm on your PATH — dsh plugin forwards profile package operations to pnpm.

dsh plugin --profile web add dsh-last-turn-delete

Installs the npm package into the web profile and activates it as a bundle (the package declares dsh.bundle.patch). One command, no manual patch editing. Restart dsh web, then refresh the page.

Other profiles: replace web with the profile name, e.g. dsh plugin --profile <name> add dsh-last-turn-delete.

Behavior

• Button: the same IconTrashOutline16 the pending-message queue uses, inserted into the message action strip right next to the copy button; it clones the native action button's class, so its resting/hover look matches the copy button exactly (no custom colors). Works in every conversation — old or new — while the session is open in the GUI.
• Delete flow: click the trash can → a small confirm bubble (确认删除 / 取消; Esc or clicking elsewhere cancels) → confirm → the host soft-deletes and the button moves to the previous item.
• Walk-back: repeat; the chain walks backward through failed-compact cards and user turns until a real (successful) compact boundary or no user message remains.
• Persistence: deleted user messages are re-derived from the log on reload; deleted failed-compact ids stay in the sidecar — dimmed state and button placement survive page refreshes.
• Safety: the host decides the deletable tail via the tail Remote (which folds in streaming, boundaries and prior deletions) and only deletes while the agent is idle; a stale click is rejected and the UI re-anchors on the real tail.

How it works

browser (client half)
  trash button on the newest deletable row (message action strip)
    click → inline confirm bubble → delete
        │  lastTurnDelete/delete        { sessionId, messageId }
        │  lastTurnDelete/deleteCompact { sessionId }
        ▼
host (lib/index.js, lastTurnDelete Remote service)
  delete            agent.runMaintenance (idle-only, serialized with the driver)
                    session.surface.nodes → last on-surface user message
                    session.append("user/message", marker, {
                      surfaceOp: { op: "replace", start, end },
                      sourceEventSeqs: shadowed
                    }) + ctx.sessions.flush()   ← the span leaves the surface
  deleteCompact     newest failed /compact group → sidecar record
  tail              newest deletable item + agent running flag
  deleted           previously deleted messages + forgotten compact ids

Host-authoritative answers travel back over lastTurnDelete/tail: the newest deletable item ({kind: "message", messageId} / {kind: "compact", commandId} / {kind: null}) plus running. Pure selection logic lives in lib/core.js (unit-tested, no DSH runtime dependency); the marker/user-message payloads use the plugin's own source identity so compaction checkpoints are never mistaken for deletions. All button/popover styling is inline on created nodes — injected <style> blocks are managed by the host module system and cannot be relied on.

Development

pnpm install
pnpm test     # node:test pure-function tests, no DSH runtime dependency

Publishing

cd plugins/dsh-last-turn-delete
pnpm publish --access public