MCP tasks, dynamic tool snapshots, and full JSON Schema compatibility

[shanev]

Context

The #5 spike freezes one paginated tools/list snapshot per run and maps the schema subset Droste can represent without invention. Advanced MCP features should not make bindings mutate mid-run or leak transport vocabulary into the Capability ABI.

Scope

• MCP task lifecycle as brokered asynchronous capability outcomes;
• listChanged and tool refresh between runs/sessions, never mutation of an active run manifest;
• manifest revision/digest negotiation and stale-session behavior;
• explicit JSON Schema dialect/provenance and compatibility reporting;
• lossless handling or typed rejection of advanced input/output schema constructs;
• deterministic raw operation identity and separately derived Python binding names.

Acceptance criteria

• Active run manifests remain immutable when a server advertises changes.
• Task polling/cancellation uses Capability execution context: cooperative cancellation and incremental accounting #89 execution context and One budget object: replace max_depth/max_calls/max_iterations constants with a caller-set compute ledger #4 budget accounting.
• Unsupported schema features fail explicitly rather than being weakened silently.
• Equivalent schemas generate deterministic bindings and prompt text.
• Cross-language/transport conformance tests pin manifest digests and normalized outcomes.

Depends on #5, #9, #13, #73, and #89.