Every workspace template (langgraph, claude-code, hermes, etc.)
subclasses BaseAdapter. Renaming, removing, or re-typing a method
on the base class silently breaks templates: the override stops
being recognized as an override; the old method-name's caller
silently invokes the default no-op; the new method-name is
unimplemented in templates that haven't migrated.
Recent #87 universal-runtime + #1957 recordResource refactor both
renamed/added methods. Without a frozen snapshot, the next rename
ships quietly and surfaces only when a template's CI catches the
AttributeError days later — long after the merge window for an
easy revert.
This snapshot pins BaseAdapter's public method surface against a
checked-in JSON file. Same-shape pattern as PR #2363's A2A
protocol-compat replay gate, applied to a Python public-API
surface instead of JSON message shapes. Both close drift classes
by snapshotting the structural surface that consumers depend on.
Two tests:
1. test_base_adapter_signature_matches_snapshot — full
introspection diff against tests/snapshots/adapter_base_signature.json.
Drift = test failure with both expected + actual JSON in
the message so the reviewer sees what changed.
2. test_snapshot_has_required_methods — defense-in-depth: even
if both the source AND snapshot are updated together
(intentional API removal), this catches removal of the
short list of methods that EVERY template depends on (name,
display_name, description, capabilities, memory_filename).
Removing one of these requires explicit edit to the
`required` set with a justification.
Verified the gate fires red on a deliberate rename
(memory_filename → memory_filename_RENAMED) — failure message
shows the full snapshot diff including parameter shapes and
return annotations.
Updating the snapshot is the explicit acknowledgment that a
template-affecting API change is intentional. Reviewer of the
introducing PR sees the snapshot diff and decides whether
template repos need coordinated updates.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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