fix(#601,#602): row nouns without mode names; trajectory shapes and shows what turns did

[justrach]

What changed

• Line REPL tool rows: remaining rendering after ADR 0019 #601 — interpretJson no longer surfaces the CodeDB mode name verbatim. A content-bearing read now interprets as 161 lines instead of lines · 161 lines (tautology) or full · 72 lines; modes that are themselves the fact (outline, symbol) stay.
• Harness observability: /trajectory cannot show what the model did #602 (2 of 5 slices) —
  • finalResponseShape broke its backward walk on a trailing bare function_call_output, so every tool-using turn whose history ends on tool results (turn cut after execution, crash, attempt_completion's final call) archived resp_blocks=0 — indistinguishable from an empty turn. Those items are now skipped; the shape describes the last model-authored run.
  • /trajectory printed only turn N ✓ 95s · prompt <sha> · <task>. The row now appends what the node already carried: model calls, tool count, tool errors, cache-hit percent, and response shape (text+reasoning), when present.
  • commands_session.zig crossed the 600-line ceiling with the above; the /trajectory handler moved verbatim into commands_trajectory.zig.

Why

The recorder bug made the DGM archive lie about tool-using turns: #270 added resp_* precisely to separate 'text-only refusal' from 'empty turn', but the Responses+tools path defeated it, so a history ending on tool results was never covered by a test. And /trajectory is the human inspect path — it ignored fields already on the turn node, leaving a run unreadable compared with a grok-build session folder.

Out of scope (kept open on #602)

Live turn stubs in the DGM file, periodic session-transcript flush, and first_token/call_id on operational traces. Behavior lifecycle (turn_committed/run_finished) already landed earlier. Click-to-expand for line-REPL rows (#601's progressive disclosure) stays out per ADR 0019 — /debug remains the raw path.

Verification

• New tests: mode-noun cases in agent_tool_label.zig; cut-after-execution shaping case in mainloop_trace.zig. Updated the one render test that asserted the old section · N lines string.
• zig build test green; scripts/eval-tier1.sh green locally (twice) and via the pre-push hook.

[justrach]

Closing as landed on tip. Row nouns without mode names (161 lines not lines · 161 lines) and finalResponseShape skipping a trailing bare function_call_output are already in agent_tool_label.zig / mainloop_trace.zig. Dirty vs main; no unique leftover.