Port OpenCode restore/activity residual subset

[danshapiro]

Summary

• Ports the remaining clean OpenCode/restore/activity residual from stale PR Stabilize dev green and canonical agent recovery #342 onto origin/main.
• Preserves OpenCode resume model identity by not passing default or inferred model args when resuming an existing OpenCode session.
• Allows restored OpenCode viewport hydration to request full replay instead of applying the generic 128 KiB cap.
• Keeps focused test cleanup for canonical session-id shapes and real-provider test routing/harness stability.

Source content

Preserved:

• 035a6949 -> e6c2cf33: canonical session ids in focus/history tests.
• ec021780 -> c57a9c33: OpenCode resume model identity plus related real-provider harness/server-suite routing.
• fdcc0bfd -> 15c3f4dc: OpenCode viewport hydration replay should not be capped.

Intentionally omitted as already covered elsewhere:

• 3eee0a7f: OpenCode activity UI signal/protocol/sidebar pieces are covered by PR Fix OpenCode ownership and restart recovery #336.
• 9d087749 and 2279caec: restore fallback lifecycle and tighter terminal restore contract work are covered by PR Fix OpenCode ownership and restart recovery #336; Codex-adjacent restore coverage is also in PR Port Codex app-server durability subset #352.
• 534d9976 and a974fe79: OpenCode contract version and attach JSON-event notes/tests are covered by PR Fix OpenCode ownership and restart recovery #336.
• a740a56f: pane recency sidecar persistence is already represented by PR fix: skip persist on cross-tab recency prune to prevent ping-pong #333, so this branch does not duplicate the tab-recency dependency stack.
• 3625e4f1: deliberately not preserved; it was reverted by 86232c00, and PR Fix OpenCode replay-gap restore on main #348 is the cleaner replay-gap carrier.

Dependencies and overlap

• Based directly on origin/main; no runtime dependency on PR Port fresh-agent foundation to main #350, PR Port fresh-agent canonical recovery subset #351, or PR Port Codex app-server durability subset #352.
• This PR does not modify PR Fix OpenCode ownership and restart recovery #336, PR Fix OpenCode and Codex session resilience #338, PR Port MCP editor pane parity to main #347, PR Fix OpenCode replay-gap restore on main #348, PR fix: recover from stale Vite chunk load failures #349, PR Port fresh-agent foundation to main #350, PR Port fresh-agent canonical recovery subset #351, or PR Port Codex app-server durability subset #352.
• If PR Fix OpenCode replay-gap restore on main #348 merges first, this branch may need a small rebase in src/components/TerminalView.tsx; the behavior is complementary, not a replay of the reverted 3625e4f1 approach.

Verification

• git diff --check origin/main..HEAD
• FRESHELL_TEST_SUMMARY="task12 opencode residual client focused" npm run test:vitest -- test/unit/vite-config.test.ts test/unit/client/components/TerminalView.lifecycle.test.tsx test/e2e/sidebar-click-opens-pane.test.tsx --run passed: 87 tests.
• npm run typecheck:client passed.
• npm run build:client passed with existing Vite chunk-size/dynamic-import warnings.

Blocked on current origin/main baseline:

• FRESHELL_TEST_SUMMARY="task12 opencode residual server focused" npm run test:vitest -- test/unit/server/terminal-registry.test.ts test/unit/server/run-standard-tests.test.ts --run did not execute tests because server global setup runs npm run build:server, which fails in unchanged server/mcp/freshell-tool.ts at lines 73 and 472.
• npm run typecheck:server fails on the same unchanged server/mcp/freshell-tool.ts parse errors.

Real provider contract tests were not run; they exercise installed provider CLIs and external provider configuration.