dsh-session-rewind

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Rewind the conversation you are in — same session, no fork, no new tab.

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DSH's official flow for "undo a few turns" is either a new fork or hand-editing state. dsh-session-rewind adds a single command — /rewind — that folds the tail of the current conversation away in place. The sessionId never changes, the event log stays append-only, and the model genuinely forgets the folded turns on its next request.

This is not a fork. Nothing is deleted from disk, no .jsonl is rewritten, no new session appears in the sidebar.

Why rewind?

Scenario	Before	With dsh-session-rewind
Bad turn, want a clean retry	Start a new session, lose context	/rewind 1, keep everything before it
Prompt went sideways mid-thread	Fork and re-explain	/rewind 3, continue in place
Trim a long exploration	Manual pruning	One click in the turn action row

Key Features

• In-place fold — session.append('user/message', checkpoint, { surfaceOp: 'replace' }); sessionId unchanged.
• Append-only log — every earlier event keeps its seq; the only write is one checkpoint event.
• Model-visible — folded nodes drop out of deriveMessages(), so the next request really lacks them.
• Two entry points — /rewind [<turn>] command, plus an icon button in the official conversation.chat.assistant-actions row.
• Safe by default — refused while the agent is running, single-flight per session, and a failed persist reports PERSIST_FAILED instead of pretending success.
• Zero extra runtime deps — Host half imports nothing; Client half requires only react.

Install

git clone https://github.com/ixietv/dsh-session-rewind.git "$HOME/.dsh/plugins/dsh-session-rewind"

Then restart DeepSeek Harness. The Loader picks up cordis.patch.yml and inserts the Host row; the Web shell loads lib/client.js via dsh.client.platform: "web".

Usage

Entry	Syntax	Behaviour
Command	/rewind	Rewind past the most recent turn
Command	/rewind 3	Rewind to before turn 3
UI	Turn action-row icon	Hover a turn, click to rewind to it

How It Works

User: /rewind <turn>
   │
   ▼
Host (lib/host.js) ── validate turn, agent idle, no rewind in flight
   │
   ▼
Locate target turn/start seq ── collect every surface node up to the tail
   │
   ▼
session.append('user/message', checkpoint, { surfaceOp: 'replace', sourceEventSeqs })
   │
   ▼
ctx.sessions.flush(session) ── persist; failure → PERSIST_FAILED
   │
   ▼
Client (lib/client.js) ── hide folded DOM rows, mark via sessionStorage

Architecture

dsh-session-rewind
├── lib/host.js            # Host half: register /rewind, compute cut point, append checkpoint
├── lib/client.js          # Web client half: action-row button, DOM hiding, rewind marks
├── cordis.patch.yml       # Loader patch: insert one Host row (no override/isolate)
├── docs/design.md         # Round-2 contract: semantics, decisions DEC-1..DEC-12
├── docs/research.md       # Surface-primitive and command-system research
├── docs/research-truncate.md  # Truncation / tool-pairing semantics
└── docs/verification.md   # Verification log and acceptance evidence

Module	Responsibility
lib/host.js	Owns the command, the cut point and the single surfaceOp: replace append
lib/client.js	Owns the trigger surface and the visual disappearance of folded rows
cordis.patch.yml	Composes next to official modules instead of replacing them

Design Notes

• Cut point is a turn boundary — satisfies tool-pairing balance without patching.
• Checkpoint source is { kind: 'user' } — inside the closed MessageSourceMap; it is not rendered as a user bubble because replace checkpoints are not "append surface" events.
• No restore/undo-of-rewind — a second rewind can only go further back, since the folded nodes are already gone from the surface.

Development

node --check lib/host.js
node --check lib/client.js

FAQ

Does this create a new session? No. The whole point is that it does not.

Is history deleted from disk? No. Events stay; only the derived surface stops exposing them.

Can I undo a rewind? Not in-place. The folded nodes are no longer on the surface.

License

MIT