Records reasoning start and end times on persisted reasoning
`ChatMessagePart`s so reasoning duration can be computed for stored
chats. Backend-only: no SSE changes and no frontend rendering ship in
this PR.
The `created_at` field on `ChatMessagePart` is extended to also be
present on `reasoning` parts (it previously appeared only on `tool-call`
and `tool-result`), and a new `completed_at` field is added for
`reasoning` parts.
### How timestamps are recorded
- `StreamPartTypeReasoningStart`: stamp `startedAt = dbtime.Now()` on
the active reasoning state.
- `StreamPartTypeReasoningEnd`: stamp `completedAt = dbtime.Now()` and
append both into parallel `[]time.Time` slices on `stepResult`.
- Persistence reads the slices in occurrence order (reasoning has no
provider-side ID) and applies them to the matching `ChatMessagePart` via
`buildAssistantPartsForPersist`. The first reasoning block's stamps go
onto the first reasoning part, and so on.
- `flushActiveState` flushes partial reasoning interrupted before
`StreamPartTypeReasoningEnd` with `startedAt` from the active state and
`completedAt = dbtime.Now()` at the interruption.
### Why two fields, not one?
Tool calls and results are point events. The frontend computes their
duration by subtracting the call's `created_at` from the result's
`created_at`. Reasoning is one assistant part that brackets a span, so
we record both endpoints on the part itself.
### Why not stamp in `PartFromContent`?
Same rationale as #24101: `PartFromContent` is called during both SSE
publishing and persistence. Stamping there would yield incorrect
persistence-time timestamps for reasoning blocks that finished much
earlier in the step. Instead we capture in the chatloop and apply during
persistence.
<details><summary>Implementation plan</summary>
- `codersdk/chats.go`: extend `CreatedAt`'s `variants` to include
`reasoning?`; add `CompletedAt *time.Time` with `variants:"reasoning?"`.
- `coderd/x/chatd/chatloop/chatloop.go`: extend `reasoningState` with
`startedAt`; extend `stepResult` and `PersistedStep` with parallel
`[]time.Time` reasoning slices; stamp on
`ReasoningStart`/`ReasoningEnd`; thread the slices through all
`PersistStep` call sites including the interrupt-safe path; record
partial reasoning in `flushActiveState`.
- `coderd/x/chatd/attachments.go`: walk reasoning parts in occurrence
order and apply `step.ReasoningStartedAt[i]` to `part.CreatedAt` and
`step.ReasoningCompletedAt[i]` to `part.CompletedAt`.
### Tests
- `codersdk/chats_test.go` round-trips `created_at` + `completed_at` on
reasoning parts and verifies omission when absent and partial
interrupted parts.
- `coderd/x/chatd/chatprompt/chatprompt_test.go` asserts
`PartFromContent(ReasoningContent{})` does NOT stamp timestamps.
- `coderd/x/chatd/chatloop/chatloop_test.go`
`TestRun_ReasoningTimestamps` drives a stream with two reasoning blocks
and verifies parallel slices, monotonicity, ordering, non-zero values,
and content-block ordering.
`TestRun_InterruptedReasoningFlushesTimestamps` cancels mid-reasoning
and verifies `flushActiveState` records a non-zero pair.
- `coderd/x/chatd/attachments_test.go` covers
`buildAssistantPartsForPersist` for normal interleaved reasoning,
partial (zero `completed_at`), and missing slices.
</details>
> Generated by Coder Agents.
Co-authored-by: Coder Agent <agent@coder.com>
Stream advisor output into the advisor tool card while the nested
advisor call is still running.
This keeps the advisor implementation intentionally advisor-specific:
the parent model still receives the same final structured tool result,
while the frontend receives transient `tool-result.result_delta` parts
to render partial advisor text in the expanded card. The final persisted
chat history remains unchanged.
Refs CODAGT-322.
Generated by Coder Agents.
<details>
<summary>Implementation plan</summary>
- Publish advisor text deltas from the nested `chatloop.Run` via
`RunAdvisorOptions.OnAdviceDelta`.
- Forward those deltas through `chatadvisor.Tool` with the parent
advisor tool call ID.
- Emit transient `ChatMessagePartTypeToolResult` websocket parts with
`ResultDelta` from `chatd`.
- Add `result_delta` to the generated tool-result TypeScript variant.
- Accumulate tool result deltas in frontend stream state and keep the
tool running until the final result arrives.
- Render streamed advisor advice in the existing advisor card using
streaming markdown mode, while retaining the updated advisor UI.
</details>
Moves the chat error kind taxonomy from `coderd/x/chatd/chaterror` into
`codersdk.ChatErrorKind` and types `ChatError.Kind` /
`ChatStreamRetry.Kind` so generated TypeScript exposes an SDK-owned
union, including `usage_limit`. Backend chat classification now
references the SDK constants directly while preserving the existing JSON
string values.
Keeps chat usage-limit admission failures on their existing 409 response
shape. The frontend maps structured usage-limit responses to the
SDK-owned `usage_limit` kind, uses generated `TypesGen.ChatErrorKind`
directly, and removes the local string union and alias.
**Breaking change for changelog:**
> `codersdk.Chat.last_error` now returns a structured `ChatError` object
(`{message, kind, provider, retryable, status_code, detail}`) instead of
a plain string. The chats API is experimental
(`/api/experimental/chats`), so this ships without a deprecation cycle;
consumers reading `chat.last_error` as a string must update to read
`chat.last_error.message`. SDK/generated TypeScript terminal error
payloads now use the single `ChatError` type; the live stream error
payload type is renamed from `ChatStreamError` to `ChatError`.
Persisted chat errors now carry the same provider-specific detail (kind,
provider, retryable, HTTP status, optional detail) as the live stream,
so refreshing a failed chat rehydrates with the full structured error
instead of a one-line headline.
Existing rows are migrated in place: legacy text errors are wrapped into
`{message, kind: "generic"}` so already-errored chats still render, and
rows with `last_error IS NULL` stay NULL. Internally, persisted fallback
decoding now reuses the existing `chaterror.KindGeneric` constant, with
no JSON value change.
Closes CODAGT-239
Adds an optional `CreatedAt` timestamp to `tool-call` and `tool-result`
`ChatMessagePart` variants so the frontend can compute tool execution
duration (`result.created_at - call.created_at`).
Timestamps are recorded at the correct moments in the chatloop:
- **Tool-call**: when the model stream emits the tool call
- **Tool-result**: when tool execution completes (or is interrupted)
These are passed through `PersistedStep.PartCreatedAt` so the
persistence layer can apply accurate timestamps to stored parts.
SSE-published parts also carry `CreatedAt` for real-time display.
Old persisted messages without `created_at` deserialize to `nil` — fully
backward compatible.
<details><summary>Implementation notes (Coder Agents
generated)</summary>
### Why not stamp in `PartFromContent`?
`PartFromContent` is called both for SSE publishing (correct timing) and
during persistence (wrong timing — both tool-call and tool-result would
get the same "persistence time" timestamp, yielding ~0 duration).
Instead, timestamps are captured in the chatloop at the right moments
and carried through `PersistedStep.PartCreatedAt` as a
`map[string]time.Time` keyed by `"call:<id>"` / `"result:<id>"`.
### Interrupted tool calls
`persistInterruptedStep` also stamps `CreatedAt` on synthetic error
results for cancelled/interrupted tool calls, so partial duration is
available.
### Files changed
| File | Change |
|------|--------|
| `codersdk/chats.go` | Add `CreatedAt *time.Time` field |
| `codersdk/chats_test.go` | JSON round-trip test |
| `coderd/database/dbtime/dbtime.go` | Add `TimePtr` helper |
| `coderd/x/chatd/chatloop/chatloop.go` | Track timestamps, pass through
`PersistedStep` |
| `coderd/x/chatd/chatd.go` | Apply timestamps during persistence |
| `coderd/x/chatd/chatprompt/chatprompt_test.go` | Verify
`PartFromContent` does NOT stamp |
| `site/src/api/typesGenerated.ts` | Auto-generated |
</details>
---------
Co-authored-by: Ethan <39577870+ethanndickson@users.noreply.github.com>
Adds client-executed dynamic tools to the chat API. Dynamic tools are
declared by the client at chat creation time, presented to the LLM
alongside built-in tools, but executed by the client rather than chatd.
This enables external systems (Slack bots, IDE extensions, Discord bots,
CI/CD integrations) to plug custom tools into the LLM chat loop without
modifying chatd's built-in tool set.
Modeled after OpenAI's Assistants API: the chat pauses with
`requires_action` status when the LLM calls a dynamic tool, the client
POSTs results back via `POST /chats/{id}/tool-results`, and the chat
resumes.
See [this example](https://github.com/coder/coder-slackbot-poc) as a
reference for how this is used. It's highly-configurable, which would
enable creating chats from webhooks, periodically polling, or running as
a Slackbot.
<details>
<summary>Design context</summary>
### Architecture
The chatloop **exits** when it encounters dynamic tools and
**re-enters** when results arrive. No blocking channels, no pubsub for
tool results, no in-memory registry. The DB is the only coordination
mechanism.
```
Phase 1 (chatloop):
LLM response → execute built-in tools only →
Persist(assistant + built-in results) →
status = requires_action → chatloop exits
Phase 2 (POST /tool-results):
Persist(dynamic tool results) →
status = pending → wakeCh → chatloop re-enters
```
### Validation (POST /tool-results)
1. Chat status must be `requires_action` (409 if not)
2. Read chat's `dynamic_tools` → set of dynamic tool names
3. Read last assistant message → extract tool-call parts matching
dynamic tool names
4. Submitted tool_call_ids must match exactly (400 for missing/extra)
5. Persist tool-result message parts, set status to `pending`, signal
wake
### Idempotency
Tool call IDs scoped per LLM step. State machine (`requires_action` →
`pending`) is the guard. First POST wins, subsequent get 409.
### Mixed tool calls
When the LLM calls both built-in and dynamic tools in one step, built-in
tools execute immediately. Their results are persisted in phase 1.
Dynamic tool results arrive via POST in phase 2. The LLM sees all
results when the chatloop resumes.
</details>
> 🤖 Generated by Coder Agents
Replace hardcoded paths for instruction files, skills, and MCP config
with
values read from `CODER_AGENT_EXP_*` environment variables. Template
authors
configure paths via the existing `coder_agent` `env` block. The agent
resolves `~`, relative, and absolute paths locally, then serves the
resolved config over `GET /api/v0/context-config`. `chatd` fetches this
once per workspace attach and falls back to today's defaults for older
agents.
All path env vars are comma-separated, allowing multiple directories:
| Env Var | Default | Controls |
|---|---|---|
| `CODER_AGENT_EXP_INSTRUCTIONS_DIRS` | `~/.coder` | Dirs containing the
instruction file |
| `CODER_AGENT_EXP_INSTRUCTIONS_FILE` | `AGENTS.md` | Instruction file
name |
| `CODER_AGENT_EXP_SKILLS_DIRS` | `.agents/skills` | Skills directories
|
| `CODER_AGENT_EXP_SKILL_META_FILE` | `SKILL.md` | Skill metadata file
name |
| `CODER_AGENT_EXP_MCP_CONFIG_FILES` | `.mcp.json` | MCP config files |
### Example
```hcl
resource "coder_agent" "main" {
os = "linux"
arch = "amd64"
env = {
CODER_AGENT_EXP_INSTRUCTIONS_DIRS = "/opt/company/agent-config,~/.coder"
CODER_AGENT_EXP_INSTRUCTIONS_FILE = "CLAUDE.md"
CODER_AGENT_EXP_SKILLS_DIRS = "/opt/company/ai-skills,.agents/skills"
CODER_AGENT_EXP_MCP_CONFIG_FILES = "/opt/company/mcp.json,.mcp.json"
}
}
```
<details>
<summary>Implementation Details</summary>
### Architecture
Follows the same pattern as MCP tool discovery:
agent resolves locally → exposes via HTTP → chatd consumes.
**Agent-side** (`agent/agentcontextconfig/`):
- `ResolvePath` / `ResolvePaths` handle `~`, relative, and absolute path
forms; returns `""` for relative paths when baseDir is empty
- `Config` reads env vars, falls back to defaults, resolves all paths
- `GET /api/v0/context-config` serves the resolved config as JSON
**chatd-side** (`coderd/x/chatd/`):
- Calls `conn.ContextConfig()` once on first workspace attach
- Falls back to hardcoded defaults on 404 (older agents)
- Iterates instruction dirs, skills dirs using resolved absolute paths
- `LSRelativityRoot` everywhere — no more home/root juggling
### Key design decisions
- **`EXP_` prefix**: env vars use `CODER_AGENT_EXP_*` to indicate
experimental status
- **Plural names**: comma-separated vars use plural names (`DIRS`,
`FILES`); single-value vars use singular (`FILE`)
- **Defaults in `workspacesdk`**: default constants live in
`codersdk/workspacesdk/` so both agent and server reference them without
cross-layer imports
- **`skillMetaFile` persistence**: stored on context-file parts via
`ContextFileSkillMetaFile` and restored on subsequent chat turns so
custom values survive across turns
- **Working dir dedup**: `slices.Contains` guard prevents reading the
same instruction file from both `InstructionsDirs` and the working
directory
- **MCP server dedup**: first-occurrence-wins dedup prevents leaking
duplicate connections from overlapping config files
- **ResolvePath safety**: returns `""` for relative paths when `baseDir`
is empty, so `ResolvePaths` filters them out
### Files changed
| File | Change |
|---|---|
| `agent/agentcontextconfig/` | New package — path resolution + HTTP
endpoint |
| `codersdk/workspacesdk/agentconn.go` | `ContextConfigResponse` type,
default constants, client method |
| `agent/agent.go` + `agent/api.go` | Wire up endpoint, pass config to
MCP |
| `agent/x/agentmcp/manager.go` | Accept `[]string` MCP config paths,
dedup by name |
| `coderd/x/chatd/chatd.go` | Fetch config, thread through, named
returns |
| `coderd/x/chatd/instruction.go` | Accept configurable dir + file name,
`skillMetaFileFromParts` |
| `coderd/x/chatd/chattool/skill.go` | Accept configurable dirs + meta
file |
| `codersdk/chats.go` | `ContextFileSkillMetaFile` field for persistence
|
### Test coverage
- `TestConfig` (4 cases): defaults, custom env vars, whitespace
trimming, comma-separated dirs
- `TestResolvePath` / `TestResolvePaths`: including empty baseDir edge
case
- `TestPersistInstructionFilesFallbackOnOlderAgent`: backward-compat
path when `ContextConfig` returns 404
- `TestChatMessagePartVariantTags`: updated exclusion list for new
internal field
### Backward compatibility
Older agents return 404 for the new endpoint. `chatd` catches this and
falls back to today's defaults via `readHomeInstructionFile` (using
`LSRelativityHome`). Existing workspaces work with no changes.
</details>
## Summary
Skills are now discovered once on the first turn (or when the workspace
agent changes) and persisted as `skill` message parts alongside
`context-file` parts. On subsequent turns, the skill index is
reconstructed from persisted parts instead of re-dialing the workspace
agent.
This makes skills consistent with the AGENTS.md pattern and is
groundwork for a future `/context` endpoint that surfaces loaded
workspace context to the frontend.
## Changes
- Add `skill` `ChatMessagePartType` with `SkillName` and
`SkillDescription` fields
- Extend `persistInstructionFiles` to also discover and persist skills
as parts
- Add `skillsFromParts()` to reconstruct skill index from persisted
parts on subsequent turns
- Update `runChat()` to use `skillsFromParts` instead of re-dialing
workspace for skills
- Frontend: handle new `skill` part type (skip rendering, hide
metadata-only messages)
## Before / After
| | AGENTS.md | Skills |
|---|---|---|
| **Before** | Persist as `context-file` parts, reconstruct from parts |
In-memory `skillsCache` only, re-dial workspace on cache miss |
| **After** | Persist as `context-file` parts, reconstruct from parts |
Persist as `skill` parts, reconstruct from parts |
The in-memory `skillsCache` remains for `read_skill`/`read_skill_file`
tool calls that need full skill bodies on demand.
<details><summary>Design context</summary>
This is the first step toward a unified workspace context
representation. Currently:
- Context files are persisted as message parts (works)
- Skills were only in-memory (inconsistent)
- Workspace MCP servers are cached in-memory (future work)
Persisting skills as parts means a future `/context` endpoint can query
both context files and skills from the same message parts in the DB,
without depending on ephemeral server-side caches.
</details>
*Problem:* `publishChatPubsubEvent` was constructing a partial
`codersdk.Chat` that omitted `LastModelConfigID` and other fields. Go's
zero-value UUID caused the sidebar to show "Default model" for chats
received via SSE.
*Solution:*
- Extracted `convertChat`/`convertChats` from `exp_chats.go` into
`db2sdk.Chat`/`db2sdk.Chats`, alongside existing `ChatMessage`,
`ChatQueuedMessage`, and `ChatDiffStatus` converters.
`publishChatPubsubEvent` now calls `db2sdk.Chat(chat, nil)` instead of
maintaining its own copy of the conversion logic
- Added backend integration test
`TestWatchChats/CreatedEventIncludesAllChatFields`
- Added frontend regression tests for nil-UUID and valid model config ID
cases
> 🤖 Created by Coder Agents, reviewed by this human.
## Summary
Introduces a new `context-file` ChatMessagePart type for persisting
workspace instruction files (AGENTS.md) as durable, frontend-visible
message parts. This is the foundation for showing loaded context files
in the chat input's context indicator tooltip.
### Problem
Previously, instruction files were resolved transiently on every turn
via `resolveInstructions()` → `InsertSystem()` and injected into the
in-memory prompt without persistence. The frontend had no knowledge that
instruction files were loaded into context, and there was no way to
surface this information to users.
### Solution
Instruction files are now read **once** when a workspace is first
attached to a chat (matching how [openai/codex handles
it](https://developers.openai.com/codex/guides/agents-md)) and persisted
as `user`-role, `both`-visibility message parts with a new
`context-file` type. This ensures:
- **Durability**: survives page refresh (data is in the DB, returned by
`getChatMessages`)
- **Cache-friendly**: `user`-role avoids the system-message hoisting
that providers do, keeping the instruction content in a stable position
for prompt caching
- **Frontend-visible**: the frontend receives paths and truncation
status for future context indicator rendering
- **Extensible**: the same pattern works for Skills (future)
### Key changes
| Layer | Change |
|---|---|
| **SDK** (`codersdk/chats.go`) | Add `ChatMessagePartTypeContextFile`
with `context_file_path`, `context_file_content` (internal, stripped
from API), `context_file_truncated` fields |
| **Prompt expansion** (`chatprompt`) | Expand `context-file` parts to
`<workspace-context>` text blocks in `partsToMessageParts()` |
| **Chat engine** (`chatd.go`) | Add `persistInstructionFiles()`, called
on first turn with a workspace. Remove per-turn `resolveInstructions()`
+ `InsertSystem()` from `processChat()` and `ReloadMessages` |
| **Frontend** | Ignore `context-file` parts in `messageParsing.ts` and
`streamState.ts` (no rendering yet — follow-up will add tooltip display)
|
### How it works
1. On each turn, `processChat` checks if any loaded message contains
`context-file` parts
2. If not (first turn with a workspace), reads AGENTS.md files via the
workspace agent connection and persists them
3. For this first turn, also injects the instruction text into the
prompt (since messages were loaded before persistence)
4. On all subsequent turns, `ConvertMessagesWithFiles()` encounters the
persisted `context-file` parts and expands them into text automatically
— no extra resolution needed
- Changes all 41 chat method receivers in `codersdk/chats.go` from
`*Client` to `*ExperimentalClient` to ensure that callers are aware that
these reference potentially unstable `/api/experimental` endpoints.
> 🤖 This PR was created with the help of Coder Agents, and has been
reviewed by my human. 🧑💻
- Add `agents_workspace_ttl` site config (default: whatever the template
says a.k.a. `0s`)
- Expose via GET/PUT `/api/experimental/chats/config/workspace-ttl`
- Chat tool reads setting and passes `TTLMillis` on workspace creation
- Existing autostop infrastructure handles the rest (zero changes to
LifecycleExecutor, CalculateAutostop, or activity bumping)
- ⚠️ Template-level `UserAutostopEnabled=false` overrides this global
default. Not touching this.
- Frontend: "Workspace Lifetime" control in /agents/settings Behavior
tab (admin-only)
> This PR was created with the help of Coder Agents, and has been
reviewed by several humans and robots. 🤖🤝🧑💻
ChatMessagePart uses a flat struct with omitempty on all fields,
but some fields are required in their TypeScript variant (no ?
suffix in the variants struct tag). When Go omits a zero-valued
required field, the frontend receives undefined where it expects
a concrete value.
Remove omitempty from fields that are required in at least one
variant: Text, URL, MediaType, FileName, StartLine, EndLine,
Content. Fields where all variants use ? keep omitempty.
Add a sub-test to TestChatMessagePartVariantTags that enforces
this invariant via reflection so future additions cannot
reintroduce the mismatch.
Supersedes #23249
Both message parsers accepted untyped input and relied on scattered
asRecord/asString calls to extract fields at runtime. With the
discriminated ChatMessagePart union, both accept typed input directly
and narrow via switch (part.type).
parseMessageContent narrows from (content: unknown) to
(content: readonly ChatMessagePart[] | undefined), removing legacy
input shape handling the Go backend normalizes away.
applyMessagePartToStreamState narrows from Record<string, unknown>
to ChatMessagePart.
The SSE type guards had a & Record<string, unknown> intersection
that widened everything untyped downstream. Since the data comes
from our own API, the intersection was removed and all handlers in
ChatContext now use generated types directly.
Fixes tool_call_id and tool_name variant tags in codersdk/chats.go:
marked optional to match reality (Go guards against empty values,
omitempty omits them at the wire level).
Refs #23168, #23175
The flat ChatMessagePart interface had 20+ optional fields, preventing
TypeScript from narrowing types on switch(part.type). Each consumer
needed runtime validation, type assertions, or defensive ?. chains.
Add `variants` struct tags to ChatMessagePart fields declaring which
union variants include each field. A codegen mutation in apitypings
reads these tags via reflect and generates per-variant sub-interfaces
(ChatTextPart, ChatReasoningPart, etc.) plus a union type alias.
A test validates every field has a variants tag or is explicitly
excluded, and every part type is covered.
Remove dead frontend code: normalizeBlockType, alias case branches
("thinking", "toolcall", "toolresult"), legacy field fallbacks
(line_number, typedBlock.name/id/input/output), and result_delta
handling. Add test coverage for args_delta streaming, provider_executed
skip logic, and source part parsing.
Add cost tracking for LLM chat interactions with microdollar precision.
## Changes
- Add `chatcost` package for per-message cost calculation using
`shopspring/decimal` for intermediate arithmetic
- **Ceil rounding policy**: fractional micros round UP to next whole
micro (applied once after summing all components)
- Database migration: `total_cost_micros` BIGINT column with historical
backfill and `created_at` index
- API endpoints: per-user cost summary and admin rollup under
`/api/experimental/chats/cost/`
- SDK types: `ChatCostSummary`, `ChatCostModelBreakdown`,
`ChatCostUserRollup`
- Fix `modeloptionsgen` to handle `decimal.Decimal` as opaque numeric
type
- Update frontend pricing test fixtures for string decimal types
## Design decisions
- `NULL` = unpriced (no matching model config), `0` = free
- Reasoning tokens included in output tokens (no double-counting)
- Integer microdollars (BIGINT) for storage and API responses
- Price config uses `decimal.Decimal` for exact parsing; totals use
`int64`
Frontend: #23037
File-reference parts in user messages were flattened to `TextContent` at
write time because fantasy has no file-reference content type. The
frontend never saw them as structured parts.
This moves all write paths (user, assistant, tool) from fantasy envelope
format to `codersdk.ChatMessagePart`. The streaming layer (`chatloop`)
is untouched, the conversion happens at the serialization boundary in
`persistStep`.
Old rows are still readable. `ParseContent` uses a structural heuristic
(`isFantasyEnvelopeFormat`) to distinguish legacy envelopes from SDK
parts. We chose this over try/fallback because fantasy envelopes
partially unmarshal into `ChatMessagePart` (the `type` field matches)
while silently losing content. A guard test enforces that no SDK part
can produce the envelope shape.
This is forward-only: new rows are unreadable by old code. Chat is
behind a feature flag so rollback risk is contained.
Also adds a typed `ChatMessageRole` to replace raw strings and
`fantasy.MessageRole*` casts at the persistence boundary. The type
covers `ChatMessage.Role`, `ChatStreamMessagePart.Role`, the
`PublishMessagePart` callback chain, and all DB write sites.
`fantasy.MessageRole*` remains only where we build `fantasy.Message`
structs for LLM dispatch.
Separately, `ProviderMetadata` was leaking to SSE clients via
`publishMessagePart`. `StripInternal` now runs on both the SSE and REST
paths, covering this.
Other cleanup:
- Old `db2sdk.contentBlockToPart` silently dropped metadata on
text/reasoning/tool-call content. New code preserves it.
- `providerMetadataToOptions` now logs warnings instead of silently
returning nil.
- `db2sdk` shrinks from ~250 lines of parallel conversion to ~15 lines
delegating to `chatprompt.ParseContent()`, removing the `fantasy` import
entirely.
Refs #22821
