Rewrite sessionNameGenerator.ts to consume a StreamFn-shaped dependency
(sourced from PiAgentSession.agent.streamFn, wired in leg B) instead of
ModelRegistry plus a dynamic @earendil-works/pi-ai/compat import.
streamFn resolves auth/headers/retry internally, so the explicit
modelRegistry.getApiKeyAndHeaders(model) call and apiKey/headers stream
options are no longer needed.
Deletes now-dead compat-loading machinery: getPiAiProviderRegistryModule,
loadPiAiProviderRegistryModule, importOptionalPiAiModule,
isModuleUnavailableError, hasGetApiProvider, PI_AI_COMPAT_MODULE,
ModuleImporter, SessionNameApiProvider, PiAiProviderRegistryModule, and
the module-level provider registry cache.
Updates the maybeGenerateSessionName call site in piSessionService.ts to
pass session.agent.streamFn instead of this.modelRegistry, and updates
both test files: sessionNameGenerator.test.ts gains coverage for the new
streamFn-driven generateShortSessionName signature (success and error
paths), and piSessionService.test.ts gains an end-to-end test proving a
first prompt generates a session name through the wired agent.streamFn
fake.
sessionNameGenerator.ts no longer imports @earendil-works/pi-ai/compat
or references getApiProvider anywhere.
Add a narrow `agent: { streamFn: StreamFn }` field to the PiAgentSession
interface, sourced structurally from the real AgentSession.agent (Agent,
from the stable @earendil-works/pi-agent-core package). This is the
resolved-auth/headers/retry "call this model" function pi's own
compaction/branch-summarization code uses internally, and will let
sessionNameGenerator.ts drop its dependency on the deprecated pi-ai
/compat provider registry in a follow-up leg.
No adapter object was needed: AgentSession's real .agent field already
structurally satisfies the new narrow shape, so defaultCreateAgentRuntime
needed no changes.
Adds a unit test proving the field is wired end-to-end via the injected
runtime creator. sessionNameGenerator.ts itself is untouched (leg C).
