dsh-context-diet

dsh-context-diet

A DeepSeek Harness (DSH) bundle that elides stale, oversized tool results from the model-visible session surface and shows what it saved in the composer footer.

It is a port of pi-context-diet (MIT, Copyright (c) 2026 sorinirimies) to DSH's durable session-surface model. The policy core is a line-by-line port; the adapter translates DSH events into the message shapes that core expects.

The goal is not only fewer tokens. A long session re-sends build logs, file dumps and exploration noise on every step, and that noise competes with the material the model actually needs. Removing it when the prompt cache is already cold keeps the working set small and the model focused, at no cache cost.

• Status: enabled by default, Host + Client bundle, no build step.
• Version anchor: developed against @deepseek-ai/dsh 0.2.1-rc.5.

What it does

At the pre-step phase the plugin looks at the current session surface, and when the prompt cache is cold — the last assistant message is older than cacheTtlMinutes — it replaces old, large, plain-text tool/result nodes with a deterministic stub.

A stub keeps the tool identity, the original size, a few tail lines and any error lines, so an exit status or a failure survives:

[context-diet: the output of bash npm test (5.0 KB, 120 lines) was elided from the
context to save tokens. Re-run it if you need it again.
error lines:
  error[E0432]: unresolved import `x`
last lines:
  BUILD FAILED in 4s
  exit code 1]

The replacement is a 1:1 durable tool/result surface replacement (surfaceOp: { op: 'replace', startSeq, endSeq }, sourceEventSeqs: [seq]), preceded by the native pruner's log-only compaction/prune shadow price. The original event stays in the log; only the model-visible copy is shorter.

The footer

The composer footer shows the same three facts pi's status line shows:

State	Text
Nothing elided yet	🥗 −12.4k at the next pause (what the next cold start would drop)
Nothing to elide	🥗 on
After a pass	🥗 −1.9k /req · 286.0k saved
A tool had to be re-fetched	… ↺3
mode: always	… ⚠ mode always

−x /req is what the current surface saves on every request; y saved is the cumulative total over the session; ↺n counts re-fetches. The footer hides itself when enabled: false or showStatus: false.

Protection: what is never elided

The gates are the upstream ones, in the upstream order:

Gate	Rule
Cache warmth	Only when the last assistant message is strictly older than cacheTtlMinutes; no timestamp means never.
Recency	Results from the last keepTurns assistant turns stay.
Size	Results below minChars stay.
Errors	keepErrors: true (default) keeps every failed result, whatever its size.
Tools	neverElide names are never touched.
Rich content	Images, attachments and any non-plain-text block are never touched.
Growth	A stub must be strictly smaller than what it shadows, or the replacement is refused.
Re-fetch feedback	When an identical call is re-issued after elision it is counted; at more than recoveryThreshold of a tool's elided results (with at least 5 samples) that tool is protected for the rest of the session.
Failure	Any error in the pre-step fails open: the turn continues untouched.

Commands

Command	Effect
/context-diet	Status: settings, per-request and cumulative savings, cold starts, recovery.
/context-diet show	What is elided now, and what the next cold start would take.
/context-diet on / off	Toggle for this session.
/context-diet now	One pass on the next step, accepting one cache rewrite.
/context-diet keep <1-500>	Keep the last N turns for this session.
/context-diet ttl <1-1440>	Cache lifetime in minutes, for this session.
/context-diet mode <cold|always>	always ignores the cold gate (only for providers without prompt caching).
/context-diet args <on|off>	Reports the platform limit below; arguments are always kept on DSH.

Command changes are session-scoped. DSH keeps plugin configuration in the profile Config, so a command never rewrites it and never reloads the plugin.

Configuration

Key	Default	Meaning
enabled	true	Master switch.
mode	"cold"	cold: elide only when the prompt cache expired (free). always: ignore coldness.
keepTurns	20	Keep the results of the last N assistant turns.
minChars	1500	Results smaller than this are not worth a stub.
cacheTtlMinutes	5	Prompt-cache lifetime; a longer idle period means cold.
keepErrors	true	Keep results flagged as errors.
neverElide	[]	Tool names that are never elided.
showStatus	true	Render the composer footer.
stubTailLines	3	Tail lines kept in a stub.
stubErrorLines	3	Error lines kept in a stub.
autoProtect	true	Protect a tool whose results keep being re-fetched.
recoveryThreshold	0.25	Re-fetch share that triggers protection (0.05-1).

elideArgs is not a config key: the adapter pins it to false and the /context-diet/stats payload reports that pinned value, so status and the footer agree about what the plugin actually does.

A config override replaces the whole config block, so restate every key you keep:

- id: dsh-context-diet
  config:
    enabled: true
    mode: cold
    keepTurns: 20
    minChars: 1500
    cacheTtlMinutes: 5
    keepErrors: true
    neverElide: []
    showStatus: true
    stubTailLines: 3
    stubErrorLines: 3
    autoProtect: true
    recoveryThreshold: 0.25

Platform limits (read this)

Two upstream behaviours cannot exist on DSH, and this bundle does not pretend they do:

1. No write/edit argument elision. pi rewrites a stale write/edit tool call because it owns the per-request messages. DSH cannot: a tool call lives in a tool/call event and in the assistant message's tool-call blocks, and an assistant/message surface replacement is rejected with two mutually exclusive rules — "sourceEventSeqs must include every shadowed surface node" and "assistant/message embeds its source stream and cannot carry sourceEventSeqs". The config has no elideArgs field; status reports write/edit args kept.
2. No cache-warming arbitration. pi can ask its own cache warmer to stop; DSH exposes no equivalent seam, so there is nothing to arbitrate.

The durable-surface model also changes the mechanism, not the outcome: pi re-decides per request and re-applies to a copy, while DSH lands a replacement once. Both leave a node elided exactly once and keep the shorter prefix stable between cold starts.

Install

plugin_manager action=install_bundle target=/abs/path/dsh-context-diet, or inside a profile:

dsh plugin --profile <profile> add /abs/path/dsh-context-diet

Read the returned application and warnings. Only applied means live; restart-required needs a full exit and relaunch. Confirm the row:

dsh --profile <profile> --dump-config | grep -A3 dsh-context-diet

Verify

1. Footer. Select a session, then run document.querySelector('[data-composer-dock] [data-composer-stat="context-diet"]')?.textContent in the browser console; it equals the footer field of /context-diet/stats.

2. Slot. cordis_inspect_query with platform: "client", provider: "Slots", method: "listSubTree", input: { root: "conversation.composer.dock" } lists context-diet beside the shipped activity and usage entries.

3. Endpoint. GET /context-diet/stats returns config, stats, recovery, the calibrated chars/token and the rendered footer.

4. Log shape. A pass appends one compaction/prune record and one tool/result replacement per node, and the original event is still present.

5. Tests.

   npm test    # node --test test/*.test.js test/unit/*.test.js
   

   The suite resolves @deepseek-ai/* from an installed Harness (test/helpers/dsh.js); set DSH_NODE_MODULES to point elsewhere.

Rollback

1. Persistent: plugin_manager action=remove_bundle target=dsh-context-diet, then restart the harness. The footer disappears with the bundle.
2. Durable replacements are not reverted. The replacement nodes are already in that session's log, and the model keeps seeing the shorter surface for that session. Resume or fork from a point before the replacements, or start a new session. Any claim that disabling restores the old surface is false.
3. Nothing outside the session log is written: no config files, no workspace files.

Durable surface: what changes

Surface	Effect
Model-visible session surface	Old plain-text results become stubs, durably, for this session.
Session event log	Append-only; the original events are still there.
Human transcript	Unchanged: replacements are model-only.
Token accounting	Corrected by the compaction/prune shadow price; no private estimator.
Other sessions	Untouched.

Troubleshooting

The footer does not appear. Check, in this order:

1. Is the client half composed? cordis_inspect_query with platform: "client", provider: "Slots", method: "listSubTree", input: { root: "conversation.composer.dock" } must list an occupant { id: "context-diet", order: 2 } beside activity and usage.
2. Was this bundle ever installed without client.js? Then the module cache holds its "not a client package" verdict for the life of the Harness process, and the client half you added later cannot compose until the process restarts. Restart dsh web once; after that the verdict is positive and later reinstalls are fine.
3. Reload the page once if the bundle was installed after the page opened; the boot graph is fetched at page load.

The footer shows 🥗 on and never a number. Nothing is eligible yet: results must be older than keepTurns, larger than minChars, plain text, and the prompt cache must be cold (cacheTtlMinutes). /context-diet show explains both lists.

Known limits

• No cache-cold arbitration: the gate is idle time, an approximation of the cache lifetime, never a provider fact.
• Only plain-text tool results are candidates; rich content is never partially elided.
• A node that already carries a replacement or a shadow price is skipped, so this plugin and the native pruner never fight over the same node.
• Behaviour on DSH versions other than the anchor is unverified.
• A resumed session rebuilds its state with one pass over the log (O(log size)), once per session and again only for /context-diet show.
• The cumulative y saved total starts at zero for a new process; a resumed session knows what is elided but not how many requests the previous process saw.
• Until the first step or /context-diet command after a resume, /context-diet/stats reports zeroes; the first step fills them from the replayed log.
• An abandoned native compaction bracket older than ten minutes is cleared so a crashed compaction cannot stop elision for the rest of the session.

Design notes

Document	Contents
docs/upstream-fidelity-spec.md	Upstream behaviour specification with source line numbers.
docs/parity-report.md	Which upstream assertions the parity suite reproduces.
docs/impl-contract.md	Adapter/core interface contract.
docs/slot-report.md	Why conversation.composer.dock is the right footer slot.
docs/pi-context-diet-to-dsh-migration-plan.md	Why a direct port is impossible and how the migration was phased.

Security

• Host code runs in-process, outside the workspace sandbox: install only from a source you trust.
• The Client reads the same-origin /context-diet/stats endpoint. It writes nothing, and the endpoint refuses unauthenticated requests.
• No lifecycle scripts, no install-time downloads, no direct $DSH_HOME access, no filesystem scan and no subprocess.

License and attribution

MIT. See LICENSE. This project is a DSH port of pi-context-diet (MIT, Copyright (c) 2026 sorinirimies); the upstream copyright notice is retained. The icon is original artwork created for this bundle.

中文摘要

• 作用：在每一步开始前，把会话里「陈旧、过大、纯文本、非错误」的工具结果替换成确定性 stub；只有在提示缓存已冷（最后一条 assistant 消息早于 cacheTtlMinutes）时才动手， 所以不额外付出缓存重建成本。目的不只是省 token，而是减少噪音、提升模型专注度。
• 保护：错误结果默认保留、最近 keepTurns 轮保留、小于 minChars 保留、富内容不动、 stub 保留末尾行与错误行、重取超过阈值自动保护该工具、任何异常一律 fail-open。
• 可视化：输入框下方常驻 footer 显示 🥗 −1.9k /req · 286.0k saved ↺3， 未裁剪时显示下一次冷启动可省多少。
• 平台限制：DSH 无法改写 write/edit 工具调用参数（平台两条互斥校验），本插件不假装支持； DSH 也没有缓存保温仲裁接口。
• 默认开启；配置走 profile Config，/context-diet 命令只影响当前会话。
• 持久语义：替换会改变该会话模型可见的历史；禁用或卸载不会回滚已落盘的替换。
• 许可：MIT，派生自 pi-context-diet，声明保留在 LICENSE。