fix: restore does not exist to validation error keywords

The keyword was removed in #611 to prevent HTTP 404 messages from being
misclassified as validation errors. However, the pattern reordering
(http_error now comes before validation) already handles that — HTTP 404
messages match `http_error` first via `"http 404"` keyword. Removing
`"does not exist"` from validation caused SQL errors like
`"column foo does not exist"` to fall through to `unknown`.

Restore the keyword and add a test for the SQL case.

Caught by multi-model code review (Claude + Gemini 3.1 Pro consensus).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: anandgupta42

packages/opencode/src/altimate/telemetry/index.ts

@@ -795,7 +795,7 @@ export namespace Telemetry {
       keywords: ["status code: 4", "status code: 5", "request failed with status", "http 404", "http 410", "http 429", "http 451", "http 403"],
     },
     // altimate_change end
-    // altimate_change start — split file_stale out of validation; remove "does not exist" (was catching HTTP 404s)
+    // altimate_change start — split file_stale out of validation for cleaner triage
     {
       class: "file_stale",
       keywords: [
@@ -811,6 +811,7 @@ export namespace Telemetry {
         "invalid",
         "missing",
         "required",
+        "does not exist",
       ],
     },
     // altimate_change end

packages/opencode/test/telemetry/telemetry.test.ts

@@ -1628,13 +1628,15 @@ describe("telemetry.classifyError", () => {
     expect(Telemetry.classifyError("Invalid dialect specified")).toBe("validation")
     expect(Telemetry.classifyError("Missing required field")).toBe("validation")
     expect(Telemetry.classifyError("Required parameter 'query' not provided")).toBe("validation")
-    // altimate_change start — file_stale split out from validation; "does not exist" moved to http_error
+    // altimate_change start — file_stale split out from validation
     // These are now classified as file_stale, not validation
     expect(Telemetry.classifyError("You must read file /path/to/file before overwriting it")).toBe("file_stale")
     expect(Telemetry.classifyError("File has been modified since it was last read")).toBe("file_stale")
     expect(Telemetry.classifyError("You must read file before overwriting it. Use the Read tool first")).toBe("file_stale")
-    // HTTP 404 "does not exist" is now http_error
+    // HTTP 404 "does not exist" matches http_error first (pattern priority), not validation
     expect(Telemetry.classifyError("HTTP 404: https://example.com/page does not exist")).toBe("http_error")
+    // SQL "does not exist" matches validation (no http_error keywords present)
+    expect(Telemetry.classifyError("error: column foo does not exist")).toBe("validation")
     // altimate_change end
   })