e2e: cover managed agent lifecycle and session detail

[codeaholicguy]

Current coverage

Historical agent sessions listing is covered for Claude and Codex, but live lifecycle commands and agent session detail are not exercised end to end.

What is missing

• agent start interactive and durable modes, naming, cwd, invalid provider/mode, and tmux prerequisites
• agent list --json detection, sorting, registry names/pins, and partial adapter failure
• Running agent detail, historical agent session detail with --tail, --full, and --verbose
• agent rename, agent open, and agent kill
• Gemini, Grok, OpenCode, Copilot, and Pi session fixtures
• Packaged incremental transcript behavior for append, truncation, rotation, partial records, and corruption

Risk ranking

High: rank 4 for managed lifecycle; medium: rank 11 for adjacent detail/open/rename; session matrix and incremental safety extend existing coverage. This should complement, not duplicate, PR #163.

Recommended E2E tests

• Start/list/detail/rename/kill a fake executable in tmux and assert registry plus process cleanup after every transition.
• Generate Claude/Codex fixtures and assert session detail tail/full/verbose, ambiguous ID, and missing ID behavior.
• Add Gemini, Grok, OpenCode, Copilot, and Pi fixtures to agent sessions --all --json.
• Append, truncate, rotate, partially write, and corrupt a large JSONL while invoking sessions/detail.

Acceptance criteria

• The checklist tests are merged under e2e/.
• Tests execute the compiled CLI with isolated HOME/project state and deterministic fake provider processes.
• Process and tmux cleanup runs even after assertion failure.

Related audit findings

C1 and D6: duplicated adapter registration/capability metadata makes provider coverage drift easy. A8: Unix command dependencies need explicit E2E platform expectations. PR #163 is related tracked work.