profiles: tool_developer folds into developer ...

The profile was a duplicate on every axis we could measure. 22 of its 26
native tools were already developer's; the four it alone held —
reload_tools, create_mcp_server, test_mcp_tool, mcp_status — are 2.9 KB of
schema. Its model chain was the same seven models. Of its 14 KB prompt,
about 8 KB was copied verbatim from developer's (the whole `## Orchestration
model` block and everything from `## Editing policy` down), and most of the
remainder restated manuals/create_mcp_server.md, which already carried the
same ten-step workflow in more detail. It was not a specialisation, it was a
snapshot: `git log -S '"reload_tools"'` shows the tool lived in developer
until 61fa370 rewrote that profile around MCP and cut it off.

What kept it alive was a premise that no longer holds — that Navi's own
capabilities would be written as in-repo tools. They are MCP servers now,
and an MCP server is not a file in this repository with a life of its own:
it is an isolated process registered from mcp_servers.d/. So there is no
reason left for a profile whose only distinct feature is a toolset a general
developer profile can hold, and every reason to stop maintaining a second
prompt that drifts against the first.

- developer: + reload_tools, create_mcp_server, test_mcp_tool, mcp_status
  (24 → 28 native). Its sub-agent gains tool_manual, which is what it
  actually needed to reach the manual while writing a server — the previous
  tool_developer sub-agent had it, developer's did not.
- server_admin: + reload_tools only (24 → 25). Adding a third-party MCP
  server is something this profile does as often as developer does.
  Deliberately not to its sub-agent: reconnecting the MCP manager is a
  process-wide operation belonging to the main agent.
- The prompt and the manual took on what the deleted profile knew and
  create_mcp_server.md did not: reload_tools before the first test_mcp_tool
  (a freshly registered server is not connected, so the test fails and the
  iteration is wasted), the smoke test read by exit code — 124 means timeout
  killed a server still running, 0 means it exited on its own, usually a
  main() without parentheses — absolute command/cwd, mcp_status as discovery
  only, and the steps that stay inline instead of going to a sub-agent.

mcp_status and test_mcp_tool were built without an MCP manager, and their
fallback did `from navi.api.deps import _mcp_manager` — a name that does not
exist, so a live call raised ImportError rather than the intended "MCP
manager not available". The tools always passed a manager in tests, which is
why nothing caught it. Both now receive the manager at construction and fall
back to the live one lazily.

Sessions and profile_overrides are reassigned before the restart: agent.py
resolves the session's profile without a guard, so a deleted profile turns
every session that referenced it into an uncaught ProfileNotFound. Nothing
in the test suite pins the profile inventory, and profiles are read once at
import time — reload_tools does not re-read them — so this ships as a
restart, and the restart is also what makes it take effect.

tool_manual: a manual the agent cannot reach is not a manual ...

tool_manual asked the filesystem for the exact string the model sent, then
fell back to registry.get(). The executor already tolerated the ways models
mangle MCP names; the tool that documents them did not, so the agent calling
mcp__navi-3d__compile_scad got a schema dump while manuals/compile_scad.md sat
there unread. Resolving a name now happens in one place — resolve_tool moved
out of the executor into navi/core/tool_utils.py — so a name that works when
the tool is *called* also works when it is *asked about*. A miss suggests the
closest names instead of "not found", and a tool that exists but is not enabled
for this profile says exactly that: documenting it is still the useful answer,
but the agent must not go on to call it. params["tool_name"] was also a crash
waiting to happen — KeyError with the key omitted, AttributeError on null or a
number — and now anything that is not a usable string means "no name given",
which returns the index of manuals grouped by source.

The generated manual now renders the whole schema. An array of objects showed
as "(array, optional)" with its item shape invisible, so a model that could not
see the fields guessed them; objects, array items, oneOf/anyOf branches, enums
and defaults are all spelled out now, depth-capped. The header names the source
(native / mcp__<server>__) and says the text is a parameter contract, not a
curated manual — otherwise a thin schema reads as "this tool is simple".

Then the manuals themselves. A manual is filed under the tool's own name, and
five of the sixteen were not: write_tool.md and write_mcp_server.md documented
tools that do not exist anywhere (the tools are reload_tools and
create_mcp_server), model_3d.md documented compile_scad, render_3d.md documented
render_stl, and write_context_provider.md documented no tool at all — it is a
guide, and now lives in manuals/guides/. The prompts pointed at the same wrong
names (tool_developer's system prompt, persona_navi_code, docs/context_providers),
so fixing the files without the callers would have moved the breakage rather
than removed it. On HEAD the probe was blunt: tool_manual("mcp__navi-3d__compile_scad")
returned None and the agent got the schema; now it returns the manual.

Nothing was enforcing any of this, which is how it drifted. tests/unit/tools/
test_manual_drift.py reads the real repository tree: every manuals/*.md must be
named after a tool that exists (built-ins and tools/*.py by their name
assignments, MCP tools by @mcp.tool(name=…) in the server sources and by the
mcp_servers.d groups, whose file name is the server name), every manual must be
reachable by both its bare name and its full MCP spelling, a guide must never
shadow a tool's name, and every manuals/<x>.md or tool_manual("x") cited in a
doc or a prompt must resolve. The next rename fails the suite instead of
quietly wasting a manual.

Finally, manuals for the built-ins the agent uses most — ssh_exec, todo, memory,
plan, filesystem, notify, code_exec — written from the current schemas and the
code paths that produce the errors, so the gotchas are the real ones (todo's
`done` validation is enforced; memory's `list` returns categories, not facts;
filesystem's `delete` removes a tree with no prompt). reload_tools.md absorbs
the file format from the deleted write_tool.md, which is where a self-extension
recipe belongs now.

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