dsh-command-context

English | 中文

A /context slash command for DeepSeek Harness: type it in a session to see how much of the context window is used, how much is free, and which part of the prompt takes the most room.

Inspired by Claude Code's /context, but every number comes from the harness's own measurement instead of a parallel accounting of its own.

Context: deepseek-v4.1-flash (myapi)
[#####---------------]  253.3k / 1.00M tokens (25.3%)  measured
Free space: 746.7k tokens (74.7%)

By message type (sum 120.1k tokens)
  System prompt        2.1k  (1.8%)
  Memory files       369.0  (0.3%)
  Skills               1.1k  (0.9%)
  User messages        7.9k  (6.6%)
  Assistant replies   39.1k  (32.5%)
  Tool results        69.5k  (57.8%)

Compaction trigger: ~800.0k tokens (80.0%), 546.7k headroom

Illustrative numbers. measured means the headline figure came from reusable provider usage; estimated means it fell back to the character heuristic.

The card renders expanded by default. A command result normally lands in the generic collapsed card that needs a click to open; this plugin's client half takes over the keyed client slot conversation.chat.commandview for the context command only, so the report is simply visible. Every other command keeps the built-in card. In a composition without a chat UI the host half still works and the generic card is used.

Install

dsh plugin --profile <profile> add dsh-command-context

Or install it from the plugin directory. The bundle is Host-only — no client half, no extra services to compose:

- insert:
    - id: dsh-command-context
      name: dsh-command-context

Requires @deepseek-ai/dsh >=0.2.1-rc.5 <0.3.0-0. The command is registered globally, so it is available in every agent of that profile.

How categories are decided

Classification is per surface node, not by slicing text: every surface node already carries its own token price, so the command only has to decide which bucket it belongs to.

Event	Bucket
system/message	System prompt
user/message whose blocks are all <system-reminder> and mention workspace instructions / Instructions from: / memory root:	Memory files
user/message whose blocks are all <system-reminder> and mention skills are available / <available_skills>	Skills
user/message, any other <system-reminder> injection	Injected context
user/message, real input	User messages
developer/message	Injected context
assistant/message	Assistant replies
tool/result	Tool results

The part that matters: an instruction file (e.g. AGENTS.md) and the skills catalog each arrive as their own user/message whose only block is a <system-reminder> — they are neither part of the system prompt nor something the user typed. Leaving them in User messages inflates that line badly, which is exactly what the first version of this plugin got wrong.

The split is deliberately conservative: if a message contains even one block that is not a <system-reminder>, the whole message stays under User messages. Under-splitting beats misattributing text the user actually wrote.

Where the numbers come from

Figure	Source
Used / pressure	ctx.tokenMeter.measure(session).totalTokens — replays the durable session log, no model call
Context capacity	session.requestContext().contextWindow (the request/context record)
Free space	capacity − pressure
Breakdown	measure().nodes, classified per node; denominator is surfaceTokens (= the sum of those nodes)
Compaction trigger	min(W * 0.8, W - maxTokens - 65536), the shipped compaction-basic defaults

Occupancy follows the @deepseek-ai/dsh-token-meter definition verbatim: measured pressure ÷ the capacity of the model route that owns it.

totalTokens = baseline.tokens + surfaceDeltaTokens. When baseline.kind === 'usage' the baseline is the last request's reported usage (input + cache read/write + output); otherwise it is the fixed four-characters-per-token heuristic, which under-prices CJK text and JSON Schema documents.

The command is read-only: it never appends session events, never triggers a model call, and never mutates session state. Its lifecycle (command/run, command/done) is recorded by the command registry as log-only events.

Why the report body is ASCII-only English

A command result renders inside a <pre> with white-space: pre-wrap and a monospace font. Full-width CJK glyphs are wider than the assumed cell, and block characters such as █░ are taller than the line box — both visually collide with the neighbouring lines in that container. ASCII has a constant width of one cell, so column alignment is exact: the meter uses #/-, labels are English, and brackets are half-width.

Two languages are kept apart on purpose: the report body is English for the layout reason above, while the command's description in the slash panel is Chinese (查看当前会话的上下文窗口占用) to match built-in commands in a Chinese UI. Plugin Manager metadata ships in both languages via locale/en.json and locale/zh.json.

Limitations

• An estimate, not a bill. The headline is measured only when reusable provider usage exists. The breakdown is always per-message route pricing, so it is a different scale from the headline and will not sum to it — the By message type line prints the node total so the two can be compared.
• Tool schemas have no line of their own because they are not surface nodes. Exposing them requires reading the contextBreakdown projection (systemTokens / toolsTokens / messageTokens); this version does not.
• Compaction trigger describes the default policy's threshold and does not assert that automatic compaction is enabled in your composition.
• No capacity, no percentage. A session with no request/context record yet reports the used tokens and says plainly that it cannot compute a ratio.
• Covers the current session only; subagent sessions are not included.

Updating during development

A bundle installed from a local directory is a junction into your source tree, and the HMR watcher's default ignored includes **/node_modules — so editing the source does not hot-reload the plugin. To load a new module generation without quitting the app:

1. Toggle the plugin row off and on once (set_plugin with include:dsh-command-context, enabled: false then true). The loader re-imports the module.
2. Set DSH_CONTEXT_LOAD_STAMP=1 before launching to have the plugin append a time rev=N line to ~/.dsh/tmp/dsh-command-context.loads.log on every activation, so you can tell which generation is live. Off by default — the plugin writes nothing to your home directory otherwise.
3. If the stamp does not advance, fully quit the app from its tray icon and relaunch (closing the window only minimizes it, and the host process keeps the old module).

install_bundle answers already-installed for an existing package; replacing a version needs remove_bundle first, and that removes the junction — back up the source directory before doing it.

Development

node --check index.js
node test/report.test.mjs

The test suite uses synthetic data to assert classification (including the memory/skills split and that mixed messages are not misattributed), the occupancy arithmetic, the unknown-capacity branch, ASCII-only output, column alignment, and the absence of explanatory copy in the report.

License

MIT