MsgRail is a narrow message rail for DeepSeek Harness: one thin bar on the left of the chat for each message you sent. Hover to preview, click to jump — older messages load automatically. Full history, live, bilingual.

MsgRail（消息轨道）——DeepSeek Harness 的窄消息轨道插件：在对话左侧，为每条你发送的消息显示一根细横线。悬停看预览、点击即跳转，更早消息自动加载；全量历史、实时更新、中英双语。

中文说明见 README.zh.md

Repository / 仓库:

• GitHub: https://github.com/chou109/dsh-msgrail.git
• Gitee (mainland-China mirror — faster there): https://gitee.com/chill109/dsh-msgrail.git

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Screenshots

Demo captures from dsh web (light theme), stored in docs/screenshots/.

The message rail	Message example

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If you are a human, read this

What it does

• A very narrow rail (44px) on the left of the chat — between the sidebar and the messages, no divider; the rail background joins the conversation area.
• One thin horizontal bar per message YOU sent in the current conversation (AI replies, auto-injected context, interrupts and commands are all excluded), densely stacked and vertically centered in the rail. No text in the rail — a pure minimap of your prompts.
• The whole history is indexed — the rail fetches the complete conversation history itself, so older messages appear even before they are loaded into the chat window.
• Hover a bar → it grows longer and bolder, and an attached preview card shows your exact message text + time, auto-positioned inside the viewport (auto-injected hint blocks, such as the paste-image instructions, are hidden). Click a bar → the conversation scrolls to that message; older messages are loaded automatically first if they are not yet in the chat window.
• Scrolls when overflowing — scroll up for older messages; the view stays pinned to the latest as new messages arrive. Switching sessions reloads the rail for the new chat.
• Deliberately minimal: no collapse, no search, no session list, no separate workspace.

Manual deployment

Requires: DeepSeek Harness web profile (dsh web), rc.7/rc.8 line. No build toolchain needed.

1. Patch the host layout (one-time; re-run after every harness update):

   node scripts/patch-layout.mjs
   

   The script adds a shell.history grid column to @deepseek-ai/dsh-client-ui-layout (sized by var(--dsh-history-width), default 0px, so an uninstalled plugin costs no space). It is idempotent and reports loudly if an anchor no longer matches. The layout bundle is resolved from $DSH_HOME (falling back to ~/.dsh); pass the path explicitly (node scripts/patch-layout.mjs <path>) for non-standard layouts.

2. Copy the plugin into the profile's node_modules:

   cp -r dsh-msgrail ~/.dsh/profiles/node_modules/
   # or on Windows PowerShell:
   Copy-Item -Recurse dsh-msgrail "$env:USERPROFILE\.dsh\profiles\node_modules\"
   

3. Register the plugin in ~/.dsh/profiles/web/cordis.patch.yml (append):

   - insert:
       - id: msgrail
         name: 'dsh-msgrail'
   

4. Restart the harness (dsh web). The rail appears on the left of the chat.

How to let an AI deploy it

Tell your AI agent:

Please deploy the MsgRail plugin from https://github.com/chou109/dsh-msgrail.git (or the Gitee mirror, faster in mainland China: https://gitee.com/chill109/dsh-msgrail.git) to my DeepSeek Harness web profile. Follow the "If you are an AI, read this" section of the README exactly.

The AI section below contains the full deployment, verification and debugging instructions.

Uninstall

1. Remove the msgrail entry from ~/.dsh/profiles/web/cordis.patch.yml.
2. Delete ~/.dsh/profiles/node_modules/dsh-msgrail/.
3. (Optional) revert the layout patch by re-installing/upgrading @deepseek-ai/dsh-client-ui-layout (the column disappears automatically once the plugin's stylesheet is gone, so this is optional).
4. Restart dsh web.

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If you are an AI, read this

Mission

Deploy the dsh-msgrail plugin for a DeepSeek Harness web profile (dsh web, rc.7/rc.8 line). The deliverable is a shell.history grid column in the host layout plus a client bundle that renders a narrow message rail — one bar per user-sent message of the current conversation, with hover previews and click-to-jump.

Repository layout

dsh-msgrail/
├── package.json              # plugin manifest: dsh.client declaration + exports["./client"]
├── lib/
│   ├── index.js              # minimal cordis host half (keeps the Loader entry valid)
│   └── client.js             # the browser bundle (hand-written, follows the client-bundle contract)
├── scripts/
│   └── patch-layout.mjs      # idempotent patch for @deepseek-ai/dsh-client-ui-layout
├── README.md / README.zh.md
└── LICENSE (MIT)

How the pieces fit

• Client discovery: the harness's client-modules scans enabled Loader entries for packages declaring dsh.client, resolves exports["./client"], hashes the bundle, serves it at /plugins/<id>/client.js and injects it into the browser boot graph. The bundle registers via window.__ModuleLoader__.load({ id, factory }); the factory receives the shell's require (react, react/jsx-runtime, @deepseek-ai/dsh-client-ui-primitives).
• Layout column: scripts/patch-layout.mjs edits @deepseek-ai/dsh-client-ui-layout/lib/client.js (three edits): the grid becomes sidebar | var(--dsh-history-width, 0px) | center | details; a <div class="dsh-layout-historyCol"> renders the shell.history slot between the sidebar and the conversation; "shell.history": { kind: "single", scope: "root" } is declared. The idempotency marker is dsh-session-history (patched) (predates the rename — do NOT change it; the already-patched host layout carries it).
• Rail width: the bundle's stylesheet declares :root { --dsh-history-width: 44px } (removed automatically on unload via the loader's style-tag tracking). The hovered bar's preview is a position: fixed card measured at runtime and clamped inside the viewport (flip left on right-edge overflow, shift up on bottom overflow).
• Message data — full history, your messages only: the rail pages the whole session log itself via the paginated history RPC (session.history({ beforeSeq, maxMessages: 200 }) through ctx.sessions.binding(id)?.session) until hasMore is false, and renders one bar per user/message event whose surfaceOp === "append" and data.source.kind === "user" (assistant replies, steering, context injections and commands are skipped — the conversation UI's own discriminators), ordered by event.seq. Because it pages the log RPC directly, the index is independent of the conversation's loaded window: older messages appear even before the chat has loaded them. Live updates come from session.subscribe → a debounced (250ms) tail-page refetch merged by seq. If a future release drops the (type-private) session.history RPC, the bundle falls back to reading the conversation snapshot (session.getSnapshot() → the loaded window) and extending it with session.loadOlder() while the snapshot reports hasMore — waiting for the window to open first and re-running the walk on live updates, so the fallback never silently shows only the loaded messages.
• Preview text: extracted from the content blocks' text field; blocks that are auto-injected hints (starting with [图片附件, [系统提示：当前模型无法直接查看图片 or [用户粘贴的图片) are skipped.
• Jump: the conversation anchors rows with data-chat-anchor-key={conversationContextKey(definitionKind, id)} — the user definition is input-message (id = message id), so the key is {13}:input-message{id}. If the anchor is absent (message not yet loaded), the rail calls session.loadOlder() repeatedly (cap 60 pages) until the anchor appears, then scrollIntoView({behavior:"smooth", block:"center"}).

Deployment steps (exact)

1. Patch the layout (from the repo root):

   node scripts/patch-layout.mjs
   # the default target is resolved from $DSH_HOME (~/.dsh); or pass an explicit path:
   node scripts/patch-layout.mjs "<path>/node_modules/@deepseek-ai/dsh-client-ui-layout/lib/client.js"
   

2. Install the package:

   echo ${DSH_HOME:-$HOME/.dsh}   # e.g. C:\Users\<you>\.dsh on Windows
   cp -r dsh-msgrail "$DSH_HOME/profiles/node_modules/"   # the package folder itself
   

3. Register the Loader entry in "$DSH_HOME/profiles/web/cordis.patch.yml":

   - insert:
       - id: msgrail
         name: 'dsh-msgrail'
   

4. Restart dsh web.

Verification

• node --check passes on lib/client.js, lib/index.js, scripts/patch-layout.mjs; node scripts/smoke-test-client.mjs loads the real bundle in a shim and exercises the injected session actions (history RPC pagination/envelope, guards, snapshot read).
• Installed copy: node -e "console.log(require('<installed>/package.json').exports['./client'])" prints ./lib/client.js.
• JSON/BOM trap: package.json must be UTF-8 without BOM (the harness parses it with JSON.parse; a BOM aborts startup with Unexpected token ''). Check: grep -rl $'\xef\xbb\xbf' "$DSH_HOME" --exclude-dir=node_modules; strip: sed -i '1s/^\xEF\xBB\xBF//' package.json.
• After restart: the rail appears left of the chat; hovering shows a preview (clamped to the viewport), clicking jumps (auto-loading older pages when needed), and switching sessions reloads the rail.

Debugging

• Column missing: restart needed? msgrail in cordis.patch.yml? installed package.json declares dsh.client + exports["./client"]? layout patch marker present? browser console errors on /plugins/dsh-msgrail/client.js?
• Startup crash Unexpected token '': BOM in package.json (strip it).
• Bars ≠ your messages: the filters are surfaceOp === "append" and data.source.kind === "user"; injected/assistant/steer rows are skipped by design.
• Jump does nothing: the target may be outside the loaded window; the rail calls loadOlder() (max 60 pages); if the session has no more history the anchor cannot exist.
• Harness upgrade drift: slot names (shell.history), ctx.sessions.binding, the history RPC and the chat-node key formula are internal APIs — re-run scripts/patch-layout.mjs and re-check after upgrades.

Operations

• Version bump: edit version in package.json, re-copy the package folder to the profile's node_modules (both copies byte-identical, BOM-free). Never rewrite JSON via PowerShell Set-Content -Encoding UTF8 (writes a BOM on Windows PowerShell).
• Harness update: re-run scripts/patch-layout.mjs, restart.

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Compatibility and limitations

• Verified against the rc.7/rc.8 web profile (the current dsh web line). The paginated history RPC (session.history({ beforeSeq, maxMessages })) is still present on the Session class at runtime — it is type-private on the session face, not removed — so the rail pages the full log directly (the same approach that originally made "unloaded messages also appear" work). Should it disappear in a later release, the bundle's snapshot + loadOlder() fallback takes over (bounded walk, waits for the window to open, re-runs on live updates). Slot names, the session service API and layout internals remain private and may change in later versions.
• Requires the host-layout patch (idempotent re-apply script included).
• Fixed 44px rail (no collapse, no resizing); the rail indexes every user-sent message of the current conversation (RPC walk capped at 300 pages of 200 events; the fallback walk at ~250 user bars / 50 pages), and clicking a bar loads older pages on demand when the message is outside the loaded window.
• Only the current conversation's user-sent messages are shown.

License

MIT