dsh-cache-saver

Cache Saver

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A host + client bundle for DeepSeek Harness. Every request re-sends the whole prompt prefix — tool JSON Schemas included. This plugin shrinks the oversized ones (dispatch untouched) and then shows you where the re-sent context goes, in a settings page.

Measured on a real profile — a fresh session's first request:

Same tools, same calls. Only the manual got smaller.

Install

Close DeepSeek Harness first (it holds the desktop profile), then one command:

"<install dir>\resources\runtime\cli\bin\dsh.cmd" plugin --profile desktop add github:ium9khbep8834-maker/dsh-cache-saver

Or with npm — one command, then add "@local/dsh-cache-saver" to dsh.profile.bundles in ~/.dsh/profiles/desktop/package.json (npm cannot know about DSH bundles):

npm install github:ium9khbep8834-maker/dsh-cache-saver

Restart (or reload the page) once — the client half is imported at boot — then open Settings → Cache saver. Other profiles: same command with --profile web / --profile dsh-tui (plain dsh, no .cmd).

What it does

1. Schema slimming — the same tools, a smaller manual

On a fresh agent the plugin copies each tool definition into that agent's scope and replaces only description / parameters. execute, output.render, timeout and safety flags are inherited, so dispatch is unchanged; DeepSeek Harness does not validate arguments (the MCP server still does), so nothing is rejected. Eight frequently used rea tools are on a keepFull allowlist.

Typical result with the default config: 158 tools, 740,692 → 121,190 chars (−83.6 %), with the five monster schemas cut by 91–99 % (compare_web_captures: 155,623 → 1,392). Add mcp__github__ to shadowPrefixes and it becomes 182 tools, 776,706 → 143,679.

2. Cost attribution — where the re-sent context actually goes

It records every tool result (chars → tokens, duplicates, errors) and every billed step's usage, then derives the numbers that matter:

prompt       = input + cacheRead + cacheWrite
new content  = input + cacheWrite            ← paid at full price
equivalent   = 0.1 × cacheRead + new content ← comparable across requests

It also classifies the current context (user / assistant / tool call / tool result / reasoning) by character share, so "history is the biggest line item" is a measurement, not a guess.

3. A settings page

Settings → Cache saver shows cost per request, cache hit rate, new paid content, tool-result volume, the schema savings table, per-session stats, recommendations and a recent-events timeline. Data comes from GET /api/cache-saver/status (same origin, read-only).

Config

Put overrides in ~/.dsh/profiles/desktop/cordis.patch.yml (the durable layer):

- id: cache-saver
  name: '@local/dsh-cache-saver'
  config:
    shadowPrefixes: ['mcp__rea__', 'mcp__github__']
    maxSchemaChars: 800

Fine-tuning: minChars 700, maxDepth 3, topDescriptionChars 140, nestedDescriptionChars 60, descriptionDepth 1, maxBranches 4.

Why not just raise the cache hit rate?

Because hit rate and spending move in opposite directions here. A hit rate of 99 % means almost every token is a cheap cache read — but the denominator is whatever you keep re-sending. Deleting 136 K stable characters lowers the ceiling while genuinely cutting the bill. Track equivalent tokens, not the ratio.

Safety and limits

• Dispatch, arguments and results are untouched; only the model-facing schema copy shrinks.
• Rare deep parameters can be folded away — add that tool to keepFull, or set dryRun: true to turn the whole thing off.
• v0.3.1 still ships one payload measurement caveat: tool-result volume is attributed by chars / 4, while step costs use the provider's real usage.

Development

npm test        # unit + client checks, no harness needed
npm run check   # syntax check

License

MIT