Closes#931.
The transport was a literal passed once at the bottom of the module,
bind_native_mcp_transport(transport="stdio"), and every guard that asks
"is this a trusted native session" resolves that question through the
value bound there. The string was a constant in the authorization chain
rather than configuration, so a remote transport had no way to be
expressed and no way to be told apart from an untrusted offline import.
mcp_transport_config becomes the single source of truth: it owns the
permitted set, the default, and the resolution of deployment
configuration (GITEA_MCP_TRANSPORT) into a validated identifier. Unset
configuration still yields stdio, so existing deployments are unchanged.
streamable-http is accepted so the bind is pluggable; standing up its
listener remains #938. sse is deliberately not registered.
bind_native_mcp_transport now resolves from configuration when no
transport argument is given, validates against that one permitted set
before writing the runtime record, and pins the result. bound_transport
is the shared accessor every transport-aware guard reads; it reports the
pinned value and never the environment, so a post-bind GITEA_MCP_TRANSPORT
change cannot move what a guard observes -- the rule already applied to
the session-state root under #695 AC2. Rebinding the same identifier is
idempotent; rebinding a different one is refused, so two guards can never
disagree within one process. assert_transport_bound fails closed before
mcp.run, so an absent or invalid bind stops the server instead of serving
tools over a transport no guard can name.
The bound identifier is now recorded in durable provenance:
mutation_provenance_fields gains bound_transport, which reaches the
decision lock through mcp_session_state.save_state and the audit records
that already spread those fields. The pre-existing transport field keeps
its trust-class values, so no durable record changes shape.
assess_transport_for_auth_mint reports the bound transport through the
same accessor; its verdict is unchanged.
#956's anchor fixture and threat model are re-anchored for the lines this
change shifts, and the two boundary claims that #931 makes false -- the
"literal stdio bind" in B1 and the stdio contract at mcp_server.py:4 --
are restated. Without this the #956 guard fails, which is what it is for.
Non-goals, untouched: the remote listener (#938), per-request principal
resolution (#932), client-managed provenance policy (#934), TLS and
remote client authentication, role capability sets, repository-binding
semantics.
Tests: tests/test_issue_931_transport_bind_seam.py, 42 tests, covering
default bind, explicit stdio, the accepted non-stdio identifier, an
unregistered identifier, no bind at all, one-value agreement across
guards, post-bind environment tampering, the durable decision-lock
record, the rebind contract, and the #695 protections that must not
regress.
Full suite from the branches/ worktree: 28 failed, 5843 passed, 6
skipped, 1047 subtests. The pinned base 9b80e75c reports 28 failed, 5801
passed, 6 skipped, 1047 subtests. The failing test IDs are identical sets
-- no failure added, none fixed; the +42 passed are this PR's new module.
Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>
Remove the public allow_test_bootstrap production seam so caller-controlled
flags cannot forge native mutation provenance. Bind provenance to the resolved
canonical entrypoint path plus a live stdio transport bind; basename-only
mcp_server.py stack frames and import-only launch no longer authorize
mutations. Test-mode install_test_native_runtime is pytest-only and cannot
reach production Gitea mutation endpoints. Add AC9 regressions for both
reviewer-found bypasses and related spoof vectors.
Refs: PR #696 REQUEST_CHANGES at 253269c; issue #695 comments 11002/11005.
Bind mutation/credential paths to a process-local native MCP runtime so env
spoofing, direct imports, and offline helpers cannot reconstruct session gates
after native transport failure. Quarantine contaminated formal reviews under
controller authority and honor quarantine in review feedback, merge eligibility,
merge mutation, and canonical handoff validation. Add regression coverage for
the second (PR #694 / review 427) incident class.
jcwalker3andClaude Opus 4.8
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