chore: import upstream snapshot with attribution

.server-changes/README.md

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+# Server Changes
+
+This directory tracks changes to server-only components (webapp, supervisor, etc.) that are not captured by changesets. Changesets only track published npm packages — server changes would otherwise go undocumented.
+
+## When to add a file
+
+**Server-only PRs**: If your PR only changes `apps/webapp/`, `apps/supervisor/`, or other server components (and does NOT change anything in `packages/`), add a `.server-changes/` file.
+
+**Mixed PRs** (both packages and server): Just add a changeset as usual. No `.server-changes/` file needed — the changeset covers it.
+
+**Package-only PRs**: Just add a changeset as usual.
+
+## File format
+
+Create a markdown file with a descriptive name:
+
+```
+.server-changes/fix-batch-queue-stalls.md
+```
+
+With this format:
+
+```markdown
+---
+area: webapp
+type: fix
+---
+
+Speed up batch queue processing by removing stalls and fixing retry race
+```
+
+### Fields
+
+- **area** (required): `webapp` | `supervisor`
+- **type** (required): `feature` | `fix` | `improvement` | `breaking`
+
+### Description
+
+The body text (below the frontmatter) is a one-line description of the change. Keep it concise — it will appear in release notes.
+
+### Writing guidance
+
+These entries are public-facing - they ship verbatim in user-visible release notes. A few rules to keep them clean:
+
+- **Write for the user, not the reviewer.** Lead with what the user notices or has to do. If a reader who doesn't know the codebase can't tell what changed for them, rewrite it.
+- **One sentence is usually enough.** The body is the bullet in the changelog. If you need a paragraph, you're probably describing the implementation rather than the change.
+- **Describe behavior, not implementation.** Skip internal scopes, middleware names, library specifics, framework internals. Users care about what's different for them, not how it's wired.
+- **Never name internal tools or infra.** Observability stacks, internal services, infra components, monitoring backends, CI surfaces, AWS specifics - none of these belong in user-facing notes.
+
+Before / after:
+
+- ❌ _"The image verification step now parses the manifest's layer media types and returns a new result the finalizer rejects."_ (describes the wiring; a user can't act on it)
+- ✅ _"Deploying with an outdated CLI could produce an image that fails to start on every run. These deploys are now stopped before going live, with a message asking you to upgrade the CLI and re-deploy."_ (what the user sees and does)
+
+## Lifecycle
+
+1. Engineer adds a `.server-changes/` file in their PR
+2. Files accumulate on `main` as PRs merge
+3. The changeset release PR includes these in its summary
+4. After the release merges, CI cleans up the consumed files
+
+## Examples
+
+**New feature:**
+
+```markdown
+---
+area: webapp
+type: feature
+---
+
+TRQL query language and the Query page
+```
+
+**Bug fix:**
+
+```markdown
+---
+area: webapp
+type: fix
+---
+
+Fix schedule limit counting for orgs with custom limits
+```
+
+**Improvement:**
+
+```markdown
+---
+area: webapp
+type: improvement
+---
+
+Use the replica for API auth queries to reduce primary load
+```

.server-changes/clearer-whitelist-login-error.md

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+---
+area: webapp
+type: improvement
+---
+
+Clearer login error when an email address is blocked by the WHITELISTED_EMAILS setting: the message now explains the address isn't allowed on this instance instead of the ambiguous "This email is unauthorized".

.server-changes/consume-stale-login-errors.md

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+---
+area: webapp
+type: fix
+---
+
+Fixed stale login errors: an error from a previous login attempt (for example a rejected email address) no longer keeps reappearing on the login page and no longer makes later, successful attempts look like they failed.

.server-changes/errors-message-fallback.md

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+---
+area: webapp
+type: fix
+---
+
+The Errors page now shows better details for each error. Errors that don't carry a message — such as errors thrown without a message, or values thrown that aren't `Error` objects — get a meaningful title instead of all reading "Unknown error", and are grouped by their name (or value) rather than collapsed into a single group. The error type now shows the actual error name, and stack traces now appear where previously they were missing.

.server-changes/otlp-transform-worker-pool.md

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+---
+area: webapp
+type: improvement
+---
+
+Optionally process high-volume telemetry ingestion in parallel for higher throughput under heavy load by setting `OTEL_TRANSFORM_WORKER_POOL_ENABLED=1`. Off by default.

.server-changes/promo-credits.md

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+---
+area: webapp
+type: feature
+---
+
+Promo credits: a /promo signup landing page, redeeming a promo code when a new org selects a plan, and showing remaining credits on the usage page.

.server-changes/realtime-backend-default-env.md

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+---
+area: webapp
+type: improvement
+---
+
+Add a `REALTIME_BACKEND_DEFAULT` env var to choose the default realtime backend (`electric`, `native`, or `shadow`) for environments whose org has no per-org override. Defaults to `electric`, so existing behavior is unchanged.

.server-changes/regions-location-clarification.md

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+---
+area: webapp
+type: improvement
+---
+
+Clarified on the Regions page that a region only affects where your runs execute, not where your data is stored. This shows as a tooltip on the Location column and in the confirmation dialog when you change your default region.

.server-changes/trql-json-extract-on-output.md

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+---
+area: webapp
+type: fix
+---
+
+Query page: extracting fields from a run's output with JSON functions (such as JSONExtractString or JSONExtractInt) no longer fails with an "illegal type: JSON" error.