subagents, secrets: an honest result contract, and two leaks closed ...

A pass over the sub-agent system, plus the two findings from the previous one.

Leaks:

- `redact_args` / `is_sensitive_key` (navi/tools/_internal/redact.py) mask
  credential-shaped keys at every log site that prints tool arguments — by key
  name, for all tools, so a future MCP tool is covered without declaring
  anything. ssh_exec passwords were sitting in the prod journal in plaintext.
- `mcp_servers.d/*.json` are tracked in git and carried the scaffolding
  machine's absolute paths, so navi-3d/navi-web silently vanished from the
  toolset off that machine. They now hold project-relative paths, resolved in
  `McpClient.open_transport` — not at load time, because create_mcp_server
  round-trips every config file through save_mcp_servers.

Sub-agent result contract:

- `run_ephemeral` returns a `SubAgentOutcome` (text + status: ok, timeout,
  max_iterations, thinking_stall, user_stop, context_overflow) instead of
  `(text, bool)`. Every exit routes through `SubAgentRunner._finish`, so token
  accounting is never dropped and a partial run always carries a progress
  report — the stop-after-stream path used to return a bare string.
- `spawn_agent` renders its header from the status. Before this, every short
  run reached the parent as "hit iteration limit", and the parent repeats that
  diagnosis to the user — a timeout was reported as an iteration limit.
- `ContextTooLargeError` no longer kills a sub-agent: the parent compresses its
  own context, a sub-agent has no session to compress into, so it stops with
  `context_overflow` and hands back what it did rather than surfacing as
  "Sub-agent failed: …" with the whole run discarded.
- The result is capped at 8000 chars (head and tail kept) so a long run cannot
  flood the parent's context, and tool arguments in the progress report go
  through `redact_args`.
- The navi-3d calling convention left the runner for the server's own tool
  schemas — a generic runner should not know one MCP server's path shapes.
- Validation moved inside spawn_agent's try: a bad argument is a clean
  ToolResult the model can read, not an exception in the parent's loop.

Tests: 1636 passed, 1 skipped. New: SubAgentOutcome paths and headers, result
truncation, context overflow, clean argument failures.

agent: a profile switch now survives the turn that made it ...

switch_profile repoints the session with one narrow UPDATE, and the run's own
save() — which lands right after every tool batch, the switch's own batch
included — wrote its stale in-memory profile back over it. The post-turn
reload then read the row it had just clobbered, saw no change, and left the
turn bound to the old profile's tools: the agent called exactly the tools
switch_profile had just advertised ("Newly available: ssh_exec, terminal, …")
and got "tool not found" for every one of them. Prod shows both halves — the
session that reported two switches kept the profile it started with, and
agent.profile_reloaded appears zero times in the whole boot.

The reload now compares against the profile the run is bound to
(bound_profile_id), which set_profile cannot move, instead of against
session.profile_id, which the store either rewrites or mutates to the new
value — making the old guard false in both branches by construction. And
save() leaves the profile_id column alone on conflict: set_profile owns it
after creation, the same way name/created_at are owned elsewhere.

A tool the live tool_map does not hold is now logged (tool.not_found, with
profile and live tool count). It previously left no trace at all in the
journal, which is why this took a database dig to find.

Three tests, each verified to fail without its fix: the next LLM call is
offered the new profile's tools, save() does not rewrite profile_id, and a
missing tool is logged.

e2e fixes: tasks tool in profiles, bg timeout lift, stepIcon fix, queue semantics docs ...

E2E findings addressed:
- tasks tool was registered but not in any profile's tools.agent.native —
  added to all six profiles (agent could not check/wait/cancel bg tasks)
- detached terminal/code_exec/ssh_exec runs without explicit timeout are
  lifted to 300s: foreground defaults (20/30/60s) marked long commands
  'completed' with partial output while the process still ran
- ToolCard.vue: define stepIcon(status) — template referenced it but the
  function was missing (render crash on task_update step)
- message_queued reachability documented: WS read loop is sequential, the
  queue path is only reachable from a second socket/headless recall

agent parallelism: background tools, bg spawn_agent, parallel tool batches, message queue ...

- backgroundable tools (terminal/ssh_exec/peer/spawn_agent/code_exec) detach
  via TaskManager with per-session/global/spawn caps, rate limit and TTL
- completion delivery both ways: task_update event (out-of-band) + pending
  notes injected into the next turn; tasks tool (list/check/wait/cancel)
- parallel tool-call batches (profile-level gate, off by default) with
  ToolStarted up-front, tagged event mux, call-order results, one save,
  plus dangling tool_call repair on session load
- user message queue instead of busy error: message_queued frame,
  back-to-back drain on the same socket, headless fallback on disconnect
- pin mcp<2 (v2 renames FastMCP with breaking API changes)
- docs: tasks.md (new), websocket/api/agent/config updates, tasks manual,
  spawn_agent background param, persona contract section

Migrate MCP tool naming from mcp:server:tool to mcp__server__tool ...

The colon separator (mcp:server:tool) confuses many LLMs during
tool-calling because colons appear in schemas and URLs. Switch to
double-underscore separator (mcp__server__tool) for robust parsing.

Key changes:
- navi/mcp/tools.py: add build_mcp_name(), parse_mcp_name(), is_mcp_tool()
- navi/core/tool_executor.py: update _resolve_tool() with new helpers
  and legacy colon fallback for old sessions
- navi/core/tool_utils.py, subagent_runner.py: use build_mcp_name()
- navi/api/routes/{admin,agents}.py: prefix via build_mcp_name()
- navi/tools/{list_tools,reload_tools}.py: migrated
- All profile configs + system_prompt.txt: replace mcp: with mcp__
- manuals/{model_3d,lint_scad,render_3d,spawn_agent}.md: updated
- mcp_servers.d/gnexus-book.json: instructions updated
- docs/{api,profiles,tools,mechanics,visual.html}: updated
- tests: test_tool_executor.py and test_mcp.py aligned

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Fix gnexus-book MCP instructions and add old-format fallback in tool executor ...

- Updated mcp_servers.json gnexus-book instructions to use mcp:gnexus-book:
  prefix instead of the old mcp_gnexus-book_ format.
- Added fallback in tool_executor.py for old underscore format
  (mcp_server_tool → mcp:server:tool) so transitional models still work.
- Added unit test for the old-format fallback.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Rename MCP tools to mcp:server:tool format and restore human-readable names ...

- Core naming: mcp_server_tool → mcp:server:tool (colon-delimited)
- navi-web tools: search/view/request → web_search/web_view/http_request
- navi-3d tools: compile_scad/render_stl/lint_scad (unchanged names)
- Updated all profile configs, system prompts, docs, manuals, tests
- Added new lint_scad.md manual
- Fixed modeler_3d prompt stale references (scad_lint, model_3d, render_3d)
- All 240 tests pass

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Handle MCP tool aliases robustly