WIP: isolate provider output continuation from durable receipts

[Maximooch]

Scope

Extract output-boundary continuation from #92, based on native-tool isolation #93. No durable receipts, HTTP admission, cancellation-task tracking, or TUI changes.

The extracted implementation preserves text across LENGTH turns and honors explicit stop/configured budgets. Response usage now reuses the existing accumulator: a real Engine-loop regression proves 13 + 12 returns 25, not 12. Native tool/prose isolation remains in force.

Verification

82 offline Engine/continuation/isolation tests pass on Python 3.10 and 3.12, including the two new real-loop continuation cases. No live model calls.

Not ready to merge

• Legacy ActionXML fragments split across separate provider generations are not yet safely reassembled. The existing implementation can miss a split action; this PR does not claim to fix it.
• Decide and test the supported continuation behavior at that boundary before merging. Do not add a generic reconstruction system by default.
• Expand real-provider-adapter fake tests for interrupted/native tool arguments as needed; provider transport assembly and cross-generation continuation are distinct contracts.
• Do not treat the narrowed feat: durable Link chat acceptance and result lookup #92 as resolving output truncation: its base retains five continuation contract failures until this work lands.
• The unrelated base TUI typecheck fix is separate.

No tests are disabled or marked expected-failure to conceal these limits. Draft status is intentional.

[vercel]

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Project	Deployment	Actions	Updated
penguin	Ready	Preview	Sep 8, 2026 7:12pm UTC

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