3.5 KiB
Tool Execution Pipeline
This graph shows where policy, hooks, sandboxing, filesystem guards, result rewriting, final-outcome observation, and UI rendering fit without changing the loop. The transformable extension points are the tools/pre-execute, tools/execute, and tools/post-execute waterfalls; monotonic guards and tools/result are the owner-enforced boundaries around them.
flowchart TD
model["Assistant message contains tool-call block"]
toolCall["Session event: <code>tool/call</code><br/>logged before execution"]
presentCall["UI pending card<br/>presentCall(args)"]
pre["<code>tools/pre-execute</code> waterfall<br/>hooks, permission, sandbox"]
guards["Registered monotonic guards<br/>deny or abstain; identity protected"]
denied["deny or ask<br/>tool body skipped"]
around["<code>tools/execute</code> waterfall<br/>timeout, retry, metrics (around dispatch)"]
toolBody["Registered tool execute() body"]
fsGate["<code>fs/write-intent</code> or <code>fs/edit-intent</code><br/>tool-fs mutations only"]
owned["Tool-owned session events<br/><code>todo/write</code>, <code>fs/observed</code>, <code>hook/invoked</code>, <code>hook/result</code>, <code>tool/code-dispatch</code>"]
post["<code>tools/post-execute</code> waterfall<br/>accept, block, replace, add context"]
final["<code>tools/result</code> parallel notification<br/>frozen authoritative outcome"]
context["Buffered additionalContext<br/>context/message after all tool results"]
toolResult["Session event: <code>tool/result</code><br/>single model-facing outcome"]
allResults["All calls in the step settled<br/>and tool/result events recorded"]
presentResult["UI completed card<br/>presentResult(args, result)"]
model --> toolCall
toolCall --> presentCall
toolCall --> pre
pre -->|allow| guards
guards -->|allow| around
guards -->|deny| denied
around --> toolBody
pre -->|deny or ask| denied
denied --> post
toolBody --> fsGate
fsGate --> toolBody
toolBody --> owned
toolBody --> around
around --> post
post --> final
final --> toolResult
toolResult --> presentResult
toolResult --> allResults
allResults --> context
Filesystem read-before-edit checks live below tool-fs on the fs/* event gate; hook bridges and future permission prompts live on the generic pre/post tool waterfalls; owner policy that must not be reordered uses registered guards; and around-dispatch concerns like the tool-call timeout policy (@deepseek-ai/dsh-timeout-policy) wrap core dispatch on tools/execute. The awaited tools/result notification observes the immutable final outcome after every transform, lossless-JSON validation, and outer error normalization. That split lets the same hooks observe bash, fs, web, todo, and subagent calls without coupling those tools to one policy service. Code Mode rides the whole pipeline twice over: run_code is the reserved registry-owned transport whose body enters the pipeline, and each tool call its program makes re-enters ctx.tools.execute() — serialized one at a time, carrying the outer execution's opaque token for correlation, and logged as a tool/code-dispatch session event, with a deny surfacing to the program as a binding rejection (a sub-call's additionalContext is deliberately dropped — no safe outlet mid-run preserves call/result adjacency).
Maintenance mode: curated Mermaid flow; exact tool schemas and event signatures live in generated catalogs.