Closes CODAGT-572
## Overview
Bumps `charm.land/fantasy` to the head of `coder_2_33`
(`v0.0.0-20260617050554-2e3ddbca75dd`) and adapts `chatd` to it.
The fantasy bump:
- Syncs upstream `charmbracelet/fantasy` main (v0.31.0) into
`coder_2_33` (coder/fantasy#42).
- Mirrors the request region when prefixing cross-region inference
profiles, so a legacy (un-qualified) Bedrock model ID is prefixed for
the same region the request is actually signed for.
Pulling in the new fantasy version propagates its required transitive
dependency upgrades (aws-sdk-go-v2, OpenTelemetry, google genai,
`golang.org/x/*`, etc.) through MVS, which accounts for the bulk of the
`go.mod`/`go.sum` churn.
## chatd changes
- Thread a per-provider `Region` through `ConfiguredProvider` and
`ProviderAPIKeys` (`RegionByProvider`), and merge/prune/resolve it
alongside API keys and base URLs.
- Source the Bedrock region from AI provider settings in `chatd` and
pass `fantasybedrock.WithRegion` when a region is configured.
- Migrate the runtime Bedrock title-generation model ID to a
fully-qualified `global.anthropic.*` ID.
- Emit a `finish_reason` in the test OpenAI streaming server so streams
close on a terminal event, matching fantasy's fail-closed stream
handling.
## Heads-up: most of this is short-lived
Almost all of the `chatd` code in this PR only executes on the **direct
(non-gateway) routing path** — the branch taken when
`AIGatewayRoutingEnabled` is `false`. That flag was a transition crutch
for AI Gateway routing, and it (plus the entire direct path /
`x/chatd/chatprovider` package that backs it) is slated for removal in
CODAGT-598. Under AI Gateway routing — which is the path every
deployment is expected to run — the Bedrock region is resolved by
aibridge directly from provider settings (`cli/aibridged.go` builds
`aibridge.AWSBedrockConfig{Region: settings.Bedrock.Region}`), so none
of the region plumbing added here is reached.
Concretely, expect the following to be deleted alongside the direct
path:
- The `RegionByProvider` map, the `Region()` accessor, and the region
preservation in merge/resolve plus the region pruning in
`PruneDisabledProviderKeys` (`chatprovider.go`).
- The `fantasybedrock.WithRegion(region)` branch in `ModelFromConfig` —
only reachable on the direct path; the gateway path builds a
`fantasyanthropic` client with no region key.
- Reading `settings.Bedrock.Region` in `aiProviderConfigFromKeys`
(`chatd.go`).
- The region-specific tests in `chatprovider_test.go`, and the
`chattest`/`model_coverage` adjustments that support direct-path
testing.
What survives the cleanup (independent of routing):
- The `charm.land/fantasy` bump and its `go.mod`/`go.sum` transitive
churn.
- The fully-qualified `global.anthropic.*` Bedrock title-generation
model ID in `quickgen.go` (a runtime-valid model identifier, not
direct-path-specific).
We're landing the full change anyway so the direct path stays correct
for the remaining transition window; just don't be surprised when
CODAGT-598 reclaims most of it.
## Notes
Depends on coder/fantasy `coder_2_33` already containing the upstream
sync and Bedrock region fix (merged via coder/fantasy#42 and
coder/fantasy#43).
Ethan
0fcd9c2005