test: harden PTY spawn funnel coverage

[noogalabs]

Summary

This small UP bundle hardens three public-framework tests discovered while adopting the same surfaces downstream:

• route both production PTY consumers through prepareNodePtySpawn, with behavioral spawn tests that stub the loader and observe the real consumer boundary;
• make the AgentPTY subclass census exact (2) instead of accepting any positive floor;
• give the installer outcome matrix an explicit result type so optional preservation/lost-record fields are available without ad hoc in narrowing.

Mutation matrix

Mutation	Outcome
Replace the AgentPTY preparation call with a direct node-pty spawn	RED exactly the AgentPTY loader-boundary test; Codex consumer stayed green
Replace the Codex app-server preparation call with a direct node-pty spawn	RED exactly the Codex loader-boundary test; AgentPTY consumer stayed green
Add a third production source matching class ... extends AgentPTY	RED exactly the exact-count census (3 received, 2 expected)

The two spawn casualties execute the real consumer methods. They do not inspect source text, so commenting out or bypassing the loader call is observable behaviorally.

Verification

• npm run typecheck — PASS
• focused Vitest run covering both consumers, the subclass census, and consent outcomes — 4 files, 189 tests passed

Draft only: no merge requested in this overnight lane.

[chatgpt-codex-connector]

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