Closes #35019.

Summary

Simplifies V2 assistant fragment and provider-continuation state while preserving provider-native correlation inside @opencode-ai/llm.

• Removes textID / reasoningID from session events and projected text/reasoning parts.
• Enforces one open text and one open reasoning fragment at the Session publisher boundary.
• Fixes OpenAI Responses text lifecycle closure at response.output_text.done / completed message-item boundaries.
• Replaces nested providerMetadata with un-nested state / resultState event payloads.
• Projects tool continuation as providerState / providerResultState, with executed top-level.
• Drops the duplicate tool name from session.tool.called; session.tool.input.started.name remains authoritative.
• Publishes live session.compaction.delta events and renders the streaming summary in the TUI.
• Renames session.revert.committed.messageID to to.

Provider state is extracted using the route provider (model.provider, e.g. openai) rather than the catalog provider identity, then re-nested only when replaying history through the same model.

Fragment premise

The adapter audit found no provider-valid overlapping text/reasoning fragments in Anthropic or Bedrock recordings/contracts. OpenAI Responses appeared overlapping because completed text blocks were left open until response finish; this PR closes them at their real done boundaries and adds a sequential-message regression test. Provider block IDs remain internal to packages/llm.

Persistence

20260703200000_reset_v2_event_fragments clears V2 events, sequences, projected messages, and admitted inputs. Changed durable contracts restart at version 1.

Verification

• Schema: 10 focused tests
• LLM OpenAI Responses: 56 tests
• Core: 116 focused tests, including provider/catalog identity mismatch coverage
• TUI: 25 focused tests
• Run compatibility: 26 passed, 3 skipped
• Shell aggregate: 13 passed on top of test(core): release shell test locations #35271
• All affected package typechecks passed
• Full-repo pre-push typecheck passed
• Client and legacy SDK generators reproduced cleanly on consecutive runs
• Prettier clean; file-scoped oxlint has 0 errors

Base #35271 is a one-file test isolation prerequisite; this PR's product diff is otherwise independent.