fix(decisioning): wire sync_accounts/list_accounts dispatch to AccountStore Protocols

[bokelley]

Problem

PlatformHandler.sync_accounts and PlatformHandler.list_accounts are inherited as _not_supported stubs from ADCPHandler. Every adopter that implements AccountStoreUpsert / AccountStoreList on their platform's accounts store is invisible on the wire — both tools return OPERATION_NOT_SUPPORTED regardless of what the store declares.

Compared to e.g. provide_performance_feedback in the same handler, which properly threads through _invoke_platform_method to platform.provide_performance_feedback(params, ctx). The account dispatchers were never given the equivalent treatment.

Tracked at adcontextprotocol/adcp-client#1631.

Fix

Wire real shims that route through the documented design — AccountStore.upsert / .list, NOT platform.<method>, since LazyPlatformRouter._ACCOUNT_STORE_METHODS already excludes account ops from per-tenant delegation:

async def sync_accounts(self, params, context=None):
    upsert = getattr(self._platform.accounts, "upsert", None)
    if upsert is None:
        return self._not_supported("sync_accounts")
    tool_ctx = context or ToolContext()
    account = await self._resolve_account(None, tool_ctx)
    ctx = self._build_ctx(tool_ctx, account)
    resolve_ctx = self._make_resolve_context(tool_ctx, "sync_accounts")
    result = _call_with_optional_ctx(upsert, params, ctx=resolve_ctx)
    if inspect.isawaitable(result):
        result = await result
    return cast("SyncAccountsResponse", result)

The ResolveContext carries the caller's AuthInfo and resolved BuyerAgent — same threading AccountStore.resolve already uses, so adopter impls implementing principal-keyed gates (e.g. spec BILLING_NOT_PERMITTED_FOR_AGENT) read the principal off the canonical context.

Both upsert and list are OPTIONAL on the AccountStore. The shims surface OPERATION_NOT_SUPPORTED (via _not_supported) when the store doesn't expose them — distinct from AttributeError, which is what an unguarded getattr().() would produce.

Wire advertisement

Adds _ACCOUNT_ADVERTISED_TOOLS = {"sync_accounts", "list_accounts"} and unions it into every sales-* entry of SPECIALISM_TO_ADVERTISED_TOOLS (every sales-* claim implies an account roster — per spec, buyers must be able to reach it). The override-detection filter still drops the tools when the platform's store doesn't expose the corresponding Protocol method, so adopters who don't yet implement them aren't suddenly over-advertising.

Tests

• test_advertised_tools_covers_every_specialism_wire_tool — extended with the two new tools.
• New positive: sync_accounts / list_accounts route through to platform.accounts.upsert / .list with ResolveContext.tool_name set correctly.
• New negative: stores that don't implement the optional Protocols surface OPERATION_NOT_SUPPORTED via NotImplementedResponse — distinct from AttributeError from an unguarded getattr chain.

877 tests pass locally (pytest tests/ -k "decisioning or account or handler or platform").

Storyboard impact

Downstream sellers running the AdCP storyboard media_buy_seller/refine_products/setup against an agent that implements the optional store Protocols will see the scenario graduate from skipped (missing_tool) to graded the moment they pull this in. Verified end-to-end against bokelley/salesagent@4e62024c — MCP 31→32 passed, 28→27 skipped.

Side note

Tracked salesagent monkey-patch that this PR replaces: https://github.com/bokelley/salesagent/blob/main/core/platforms/account_polyfill.py — happy to drop the polyfill once this lands.

[bokelley]

Superseded by #610 — same core wiring, but strictly better: per-instance filter that drops the tool when the store doesn't expose the optional Protocol (with logger.info breadcrumb), wire-envelope auto-wrapping with credential scrubbing, filter-dict projection for list, plus authoring docs and credential-smuggling test coverage. Closing in favor.

[bokelley]

Acknowledged — noting the closure in favor of #610. No action needed here.

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Triaged by Claude Code. Session: https://claude.ai/code/session_0146e4vWbsnkKQ7WqUvLw3ue

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