Resolve tool availability against the boundary the distribution declares

[KimGLee]

Closes #170.

What was wrong

distribution-boundary.yaml says which files never reach an adopter runtime. Nothing in the interface compile chain read it. So the closed interface policy required every adopter to supply a tool the same repository had excluded, and compile_cli_contract failed closed when the adopter correctly did not have it. This repository cannot observe that, because it holds every tool it declares.

Both declarations were internally correct, which is why neither was the thing to change. The boundary excludes a tool whose only job is copying a template tree that is also excluded. The interface policy is a closed enumeration of the call surface, and that tool genuinely has one here. What was missing was anything that read both — grep found exactly one module in Tools/ that reads the boundary at all, and it was not in this chain.

The resolver, and what it refuses to do

Tools/tool_availability.py is the single reader. Its answer is deliberately not "skip whatever is absent". Absence is evidence of two opposite things — a tool the boundary excludes, and a carried tool that failed to arrive — and a rule that cannot tell them apart converts the second into a silent pass. partition() returns three sets, and the third (unregistered-absent) stays a refusal that names the tool, the boundary and the target.

The projection target is declared, never inferred. A distribution mid-checkout would otherwise identify itself as an adopter runtime and excuse exactly the absence that needs reporting. --projection-target is required to write. With --check it falls back to the target the stored artifact records — reading a declaration, not guessing at one — and an artifact that records no target is refused rather than assigned one.

The artifact now says whose projection it is

Four bindings, each with its own remedy, each reported as itself rather than as "stale":

binding	what a mismatch means
projection_target	another projection, not a stale copy of this one
distribution_boundary.sha256	the boundary moved; every derived artifact is stale
included_tools	compiled somewhere else; cannot stand in for a local build
excluded_tools	which absences this target was permitted

One thing the issue did not ask for, and why it is here

The foreign-artifact case was detectable but never detected: no adopter runs the interface checks. run_gates preflighted compose_vocab and compose_page_contract and stopped there. Both interface artifacts now join that freshness set — which is what turns "regenerate in the target repository" from documentation into a gate an adopter actually trips.

render_interface_projection needed no change. It already consumed only the compiled contract, so requirement 6 was already met.

Acceptance

Fourteen cases, all derived from the declaration rather than naming a tool. A test that spelled the name would keep passing after the declaration changed and would be asserting its own memory. One case fails loudly if the boundary ever declares no tool module at all, so the rest cannot go quietly vacuous.

• source-distribution includes every boundary-excluded tool, and excludes nothing.
• A generic carried-runtime fixture — built by applying the boundary to a copy of Tools/ — compiles, renders, and answers a real MCP initialize and tools/list, with every served tool backed by an implementation.
• Deleting a carried tool from that fixture still fails the compile, and the refusal names it.
• A source projection cannot be compiled where a declared tool is absent: the permission belongs to the target, not to the repository.
• Boundary drift marks the artifact stale, with the two hashes.
• Another target's artifact reports as another projection.
• A tampered included_tools reports as compiled elsewhere.

Verified before and after on the fixture from the issue: initialize went from -32002 to OK, with 39 tools served and no missing implementations.

Full suite 1,890 tests, no new failures. No adopter-specific case appears in the code or the tests.