TUI runtime supervisor resilience + memory op visibility parity

[njfio]

Problem statement

Tau TUI still exits hard when the interactive runtime child exits non-zero (for example provider invalid response / empty last message paths), and operators lose control of the session. In addition, memory operation visibility is still incomplete: TUI and web surfaces do not consistently expose turn-time memory reads/writes/deletes in a way that confirms the memory system is active.

Acceptance criteria

1. TUI resilience on child failure

• In app-renderer mode, non-zero interactive runtime child exits do not terminate Tau TUI immediately.
• TUI renders a clear runtime-failed status in UI panes.
• Operator can recover from UI via /restart local command without relaunching the whole TUI process.

2. Provider failure normalization behavior

• Failure signatures such as "codex cli failed ... no last agent message" are treated as turn/runtime failure status lines and remain visible in Assistant/Events panes.
• Error is explicit and observable; no silent fallback semantics.

3. Memory operation visibility parity

• Turn-time memory tool operations include read visibility (memory.read) in addition to existing write/delete visibility where available.
• /memory output in TUI includes recent memory activity lines so operator can verify read/write/delete activity after turns.

4. Tests

• Add/extend tests for local /restart command parsing and handling.
• Add regression coverage for memory read event mapping + /memory rendering path.

Non-goals

• Full TUI visual redesign.
• Changing provider API contracts.
• Background memory distill algorithm redesign.

[njfio]

Spec added: \n\nProceeding to RED tests for restart supervision + memory read visibility.

[njfio]

Spec added: specs/3574-tui-runtime-supervision-memory-visibility.md

Proceeding to RED tests for restart supervision + memory read visibility.

[njfio]

Implemented on branch 3574-tui-runtime-supervision-memory-visibility.

Delivered:

• TUI app-renderer no longer hard-exits on runtime child non-zero status; it now records explicit assistant/events failure lines and remains interactive.
• Added local /restart command to respawn runtime child in-place.
• Added memory read visibility end-to-end:
  • memory_read tool now maps to memory.read observer event in coding-agent runtime.
  • TUI memory local command now includes recent memory activity lines (read/write/delete).
  • TUI event parser handles memory.read and renders memory consulted (...) assistant feedback.

Spec and evidence:

• specs/3574-tui-runtime-supervision-memory-visibility.md updated to Implemented with AC checklist and test commands.