A single-model subagent has no fallbacks of its own, so it inherits one
and is pinned to a `subagent:<id>` role. That pin is inserted first in
`retry.fallbackChains` so no other role can capture its routing — which
also means it shadows every configured role chain at runtime.
Inheritance was hardcoded to `chains.default`, so a subagent spawned
through a role alias (the bundled scout's `model: "@smol"`) retried on
the default role's chain instead of its own. With `smol` chained to
composer/grok/luna and `default` chained to gpt-5.6-sol, every scout
fell back onto sol.
Resolve the inherited chain from the role identity still present in the
raw pattern (`@smol` -> `smol`), falling back to `default` when that
role configures no chain. An explicitly empty role chain still means
"no fallbacks", mirroring `expandDefaultRetryFallbackChains`. Explicit
model selectors keep inheriting `default`: they carry no role identity,
and a role assigned the same model must not capture the child's routing.
- Update hashline block resolution formatting to correctly incorporate anchor lines within operation labels.
- Fix and update test assertions and mock contexts across coding agent tests.
Reverted branch-side edits to spawn-policy prompts/tests, settings tab
groups, mermaid cache typing, prewalk todo gating, and packages/ai test
churn back to merge-base content; trimmed their changelog entries. These
repaired stale CI against an older main and are stale or conflicting
against current main.
Forward unresolved explicit subagent model selectors into child session startup so modelRoles.task cannot disappear during executor preflight and fall through to an unrelated provider default.\n\nFixes #4421
Kept OpenRouter and Vercel upstream routing suffixes in subagent retry fallback selectors so same-base routed candidates stay distinct.
Resolved retry fallback candidates from the raw selector before model switching so routed fallback models keep their requested upstream route.
Placed subagent-scoped fallback chains ahead of inherited retry chains so overlapping primary selectors prefer the explicit subagent model order.
Expanded the regression to pin fallback chain insertion order when a global chain shares the same primary selector.
Installed subagent-scoped retry fallback chains from ordered task model candidates so provider failures can advance to the next configured worker model.
Updated task result tracking to surface the fallback-applied final model and added focused regression coverage for the executor wiring.
Fixes#2750
enieuwy