[Brian Krabach (bkrabach)]

amplifier routing show misled two kinds of user. Both found 2026-09-07 while shipping routing-matrix#71; both fixed in commands/routing.py.

1. The alias-blind user

A ChatGPT-subscription-only user (openai-chatgpt module, no openai module) is routed fine at runtime — the hook's PROVIDER_FAMILY_ALIASES maps provider: openai onto that mount. But _get_configured_provider_types fed a bare set-membership test that never consulted the alias table, so the display told exactly that user "✗ not configured" for every openai role. Measured in a DTU.

Fix: _get_configured_provider_types also adds every canonical family a configured module satisfies, reading the table from amplifier_module_hooks_routing.resolver.PROVIDER_FAMILY_ALIASES itself — one home, so the display cannot disagree with the resolver. All four downstream in provider_types sites become alias-aware with no change. Guarded import: on a clean install before the bundle is first fetched it degrades to "no aliases" (pre-alias behaviour), never an error. Directional, as in the resolver.

2. The hook-less user — the one that actually bit

routing show reads matrix files straight from the bundle cache (it even lazy-fetches the bundle), so it renders a matrix as "★ active" on a host whose active bundle never mounts hooks-routing. Nothing then applies the matrix; every sub-agent silently inherits the parent's provider.

Measured on a project pinned to anchors-amp-dev — a lean base that does not include routing-matrix:

$ amplifier routing show
  general — …
    ★ openai / gpt-?.?-terra  [reasoning_effort: medium]  ← active   ← says this

delegate:agent_spawned … "provider_preferences": null              ← does this
llm:request … "model": "claude-opus-5", "provider": "anthropic"     ← explorer ran on the parent's model

Fix: _routing_hook_is_composed composes the session the way runtime/config.py does — active bundle + every app bundle, in order — but stops at to_mount_plan(): no prepare(), no module installs, no network beyond what's cached (~0.1s warm). If hooks-routing is absent, show prints:

⚠ Not applied in your sessions. The active bundle anchors-amp-dev (and your app
bundles) never mount the hooks-routing hook, so this matrix is only displayed
here -- sub-agents will inherit the parent session's provider instead.
  To apply it in every session regardless of active bundle:
    amplifier bundle add git+https://github.com/microsoft/amplifier-bundle-routing-matrix@main#subdirectory=behaviors/routing.yaml --app

(command printed with soft_wrap=True so Rich can't fold it mid-URI).

Scope guard: only runs when an active bundle is explicitly set. With none set the CLI starts its built-in default foundation, which includes routing-matrix — nothing to warn about, and skipping the composition keeps this out of every code path and test fixture that never chose a bundle. (An earlier draft composed the real foundation bundle inside the shadowing tests: 12s per invocation, and its side effects made two runs of show disagree. That's why the guard exists.) Any failure inside the check → None → prints nothing. A diagnostic must never break the command.

Verified live on the host that surfaced it

cwd	active bundle	routing show
the anchors-amp-dev project	anchors-amp-dev	warns, with the copy-pasteable command
/tmp	default (foundation)	no warning

Tests

tests/test_routing_family_alias_and_mount_warning.py (10): chatgpt alone makes openai configured · alias is directional · empty table is byte-identical to before · table is read from the hook, never copied · warning names bundle + hook + exact command · silent when composed · silent when it can't tell · detection failure degrades to None · no active bundle means no composition · remediation URI is the bundle's real behaviors file.

Full suite 1917 passed; ruff clean on touched files (the 9 pre-existing findings elsewhere are untouched).