⚡ dsh-fast

Read-only performance diagnostics for DeepSeek Harness.

Observes the session event stream — never the model hot path — and reports where latency and context budget actually go.

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Compatibility

• DeepSeek Harness 0.1.0-rc.6 (peers pinned to 0.1.0-rc.6).
• Node ^22.19.0 || >=24.0.0, ESM only ("type": "module").
• Peer dependencies: @deepseek-ai/cordis ^4.0.1, @deepseek-ai/schemastery ^3.18.0, and @deepseek-ai/dsh-session, @deepseek-ai/dsh-tools, @deepseek-ai/dsh-commands, @deepseek-ai/dsh-compaction, @deepseek-ai/dsh-storage-domain at 0.1.0-rc.6.

What you get

• Session load timing — publication-to-first-request latency, classified open (fresh) vs restore (seeded/resumed), plus the restored seed-event count.
• Spill-hit statistics — how many tool results were spilled to a session-scoped artifact (detected from the durable spill notice).
• Compaction count and trigger — total compactions, split manual (slash command) vs automatic (pressure), and total shadowed tokens.
• Context-injection volume — system-prompt (AGENTS.md + skills + persona), tool-schema, and surface tokens with their shares of the total.
• LLM cache hit rate — input / cache-read / cache-write / output tokens aggregated from provider usage, plus the derived hit rate.
• Optimization suggestions — threshold-driven notes (trim skills, tighten tool schemas, compact earlier, enable prompt caching, enable spill-policy, …).
• Async sampling — metrics are folded O(1) per event and snapshotted on a timer, never on the append path.

Quick start

git channel

# From a scratch profile (pins the commit; runs the self-contained `prepare` build)
dsh plugin --profile demo add "github:YOUR_ORG/dsh-fast#<sha>"
# The profile's pnpm-workspace.yaml gains an allowBuilds entry for dsh-fast on first add.

npm channel

dsh plugin --profile demo add dsh-fast

Both channels install the bundle row (see cordis.patch.yml) into the profile's dsh.profile.bundles stack and take effect on restart.

Install & uninstall

dsh plugin --profile demo add dsh-fast       # install
dsh plugin --profile demo remove dsh-fast    # uninstall

Verify the row mounts: dsh --profile demo --dump-config | grep dsh-fast.

Configuration

All tunables are Schemastery Config fields; invalid values fail the profile load loudly.

Key	Default	Description
enabled	true	Master switch; false mounts nothing.
privacy.includeCwd	false	Include the sanitized session working directory in reports.
sampling.snapshotIntervalMs	60000	How often active sessions are sampled (ms).
sampling.maxHistorySamples	20	Samples retained per session in the durable history.
thresholds.systemPromptTokens	20000	Warn when the system prompt exceeds this many tokens.
thresholds.toolSchemaTokens	8000	Warn when the tool schema exceeds this many tokens.
thresholds.surfaceTokens	60000	Warn when the conversation surface exceeds this many tokens.
thresholds.cacheHitRateFloor	0.1	Warn when the cache hit rate falls below this (0..1).
thresholds.compactionCountWarn	10	Warn once this many compactions have triggered.
thresholds.compactionShadowTokens	40000	Warn when the average shadowed token count per summary exceeds this.
spill.detectSpilledResults	true	Detect spilled tool results from the durable notice marker.

Tools & surfaces

• /fast — a human slash command that prints the current session's health report: load timing, spill, compaction, context-volume ranking, cache hit rate, and suggestions.
• fast_report — a model tool returning the same report as structured JSON (so the model can reason over it), with a human-readable text render.

Permissions & data

dsh-fast consumes only public seams: session/* and agent/* events, the optional ctx.tokenMeter, ctx.storageDomain, ctx.commands, and ctx.tools. It is strictly read-only over the session log — it never mutates the model request, tool results, or the session surface. Metrics are persisted to the dsh_fast storage domain (one bounded history per session), not to the session log. Report identity and the optional working directory are sanitized before any display or durable write.

Security boundaries

• Read-only, zero model-path overhead — folding is O(1) per event; sampling runs on a timer.
• No network, no credential handling — the plugin makes no outbound requests and stores nothing sensitive.
• Fail-loud configuration — every tunable is validated at mount; invalid bounds throw.
• Sanitized display/durable data — control characters are stripped and strings are budgeted; cwd is off by default and path-truncated when enabled.
• Reversible registrations — every contribution goes through ctx.effect() / ctx.on() / register(), so uninstall and hot reload are clean.

Known limitations

• Storage domain, not session events — rc.6 Session.append offers no ignorable marker and no external event-registration surface, so a custom fast/* session event would make the persistence coordinator refuse the log on restore. Metrics are therefore persisted to the storage domain; the raw events remain the reconstructable source of truth.
• Spill detection is heuristic — it reads the durable spill notice (Full … stored at:); no dedicated session event exists.
• System prompt is one bucket — AGENTS.md, skill directory, and persona are all part of the assembled system prompt; the header carries no per-section token accounting, so they are reported together.
• Load timing starts at publication — the disk-read portion of a restore happens before session/created (owned by sessionPersistence) and is not observable from this plugin's allowed events; the reported duration is publication-to-first-request.

Development

pnpm install
pnpm run typecheck && pnpm run typecheck:ci
pnpm test
pnpm run build
pnpm run verify:self-contained && pnpm run verify:artifacts
node scripts/check-readme-sync.mjs
pnpm pack

Topics

dsh, dsh-plugin, deepseek-harness, deepseek, cordis, performance, diagnostics, profiling, context-engineering, llm-cache

Contributors

dsh-fast contributors.

PerryLink DSH Plugin Family

This project is one of the 29 DeepSeek Harness plugins maintained by PerryLink. If this one helps you, the others likely will too:

Plugin	One-liner
dsh-auto-review	Second-model auto-review on the approval chain, fail-closed by default
dsh-background-agents	Durable background child agents with a Web UI sidebar, messaging and interrupt
dsh-budget	Cost governance for DeepSeek Harness: budgets, carbon, and latency in one panel.
dsh-checkpoint-rewind	Claude Code /rewind-equivalent: snapshots, session forks, one-shot restore
dsh-claude-move	Migrate Claude Code sessions, memory, skills and CLAUDE.md into DSH
dsh-click	Cross-platform native desktop control for DeepSeek Harness — Windows first.
dsh-composer-history	Terminal-style input history for the web composer: arrows, Ctrl+R search
dsh-defend	Prompt-injection, jailbreak, and secret-leak defense for DeepSeek Harness.
dsh-doublecheck	Engineering-discipline guard: requirements grill, test gates, adversary review
dsh-draw	Unified static-image generation routing for DeepSeek Harness.
dsh-fast	Read-only performance diagnostics for DeepSeek Harness.
dsh-github	GitHub PR/issues integration for DSH, every write gated by approval
dsh-library	Local document knowledge base for DeepSeek Harness.
dsh-local-ai	Local-model (Ollama) integration for DeepSeek Harness.
dsh-lsp-actions	LSP diagnostics, formatting, completion, code actions and rename over language servers
dsh-mask	PII masking middleware for DeepSeek Harness — anonymize personal data before it reaches the model, restore it at the display layer.
dsh-mcp-panel	Read-only MCP runtime panel: /mcp command + Settings tab with status, tools and errors
dsh-memento	Approval-gated cross-session memory: ctx.memory seam + SQLite + memory tool
dsh-observe	OpenTelemetry and Langfuse observability exporter for DeepSeek Harness.
dsh-output-styles	Claude Code outputStyles-equivalent runtime style switching
dsh-permission-rules	Claude Code-style declarative allow/deny/ask permission rules with audit
dsh-plugin-guide	Plugin-development knowledge base as an on-demand agent skill
dsh-score	Multi-dimensional quality scoring for DeepSeek Harness plugins.
dsh-session-pin	Pin sessions in the Web sidebar with durable ordering
dsh-session-sync	Cross-device session sync for DeepSeek Harness — a dedicated git mirror of your session store.
dsh-skill-pack-security	Security-audit skill pack: secret scan, dependency and supply-chain review
dsh-talk	Voice-first session loop for DeepSeek Harness: talk to it, hear it answer.
dsh-test-drive	Isolated install-and-smoke test drives for DeepSeek Harness plugins.
dsh-translate	Vendor parameter translation and deterministic JSON repair for DeepSeek Harness.

License

Apache-2.0 — see LICENSE.