One principle: every fact in the assembled prompt has exactly one owner.
- dsh-system-prompt: merge-extensible AssembleContext on assemble();
a variable(name, provider) registry; {{name}} interpolation in
renderPrompt, strict (unknown/valueless/malformed references throw);
duplicate section and variable names rejected; assembly carries
resolved section text + variables through the assemble waterfall.
- dsh-agent declares AssembleContext.agent; dsh-agent-loop registers
the agent:persona section (order 0 - identity renders before tool
guidance) and the model/cwd variables, and drops its string join:
renderPrompt(assembly) IS the full prompt.
- Tool guidance moves to its owners: descriptions carry per-tool
semantics; sections only cross-call habits (tool:bash exit-code
habit at order 105; read's not-shell nudge). todo/subagent need no
section - their descriptions already carry the contract.
- SubagentProvider.inheritsParentContext (spawn/acp false, fork true);
dsh-tool-subagent derives truthful per-provider wording and resolves
the provider at load (backend must be listed first).
- Example personas shrink to identity + behavior with {{model}} (and
{{cwd}} in the ACP tree); the welcome banner stops enumerating tools.
RFC: docs/rfc/implemented/architecture/2026-07-05-prompt-variables-and-tool-guidance-ownership.md
web/ - web capability family
The web access capability seam: an abstract web interface, search/fetch provider implementations, and the model-facing web tools. All product packages.
| Package | Role | ctx key |
|---|---|---|
web/ |
Abstract web seam (search/fetch provider registries + selection + vocabulary + WebError) |
ctx.web |
web-search-exa/ |
Exa-backed WebSearchProvider |
(registers on ctx.web) |
web-search-perplexity/ |
Perplexity-backed WebSearchProvider |
(registers on ctx.web) |
web-search-deepseek/ |
DeepSeek-backed WebSearchProvider using native web_search through the Anthropic-compatible API |
(registers on ctx.web) |
web-fetch-local/ |
Anonymous public HTTP(S) WebFetchProvider |
(registers on ctx.web) |
tool-web/ |
Model-facing web_search/web_fetch tool schemas |
(registers on ctx.tools) |
The interface lives at web/web/. Unlike bash/fs, the seam spans two capabilities (search and fetch) with potentially multiple providers each: ctx.web is one web-access middle layer with one provider-selection policy, one abort/error vocabulary, and one product-facing "how this harness reaches the web" config surface. Providers register capabilities, not tools; tool-web is the only owner of model-facing names, schemas, prompt guidance, and presentation. A search provider swap does not change how the model asks for a query, and a fetch implementation swap does not change how the model asks for a URL.
See the web capability seam RFC for the design rationale, including why search and fetch are deliberately one seam and why web_fetch's SSRF protection is deferred.