feat(#3653): add review.models.cursor — wire modelArg/modelConfigKey for the cursor reviewer lane (#4160)

* feat(#3653): add review.models.cursor — wire modelArg/modelConfigKey for the cursor reviewer lane

cursor-agent exposes --model (204 selectable models) but the cursor lane
declared modelArg: null / modelConfigKey: null, so review.models.cursor
was rejected as an unknown config key and the #1517 reviewer-instances
escape hatch silently discarded a configured model at modelExpansion.

Wire the lane the same way codex already is: inject {{model}} into args
right after -p, set modelArg to --model, and declare modelConfigKey as
review.models.cursor plus its config schema entry. An unconfigured lane
still invokes byte-identically to today.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* docs(#3653): add changeset for review.models.cursor

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* fix(#3653): update co-change surfaces that assumed cursor has no model key

gsd-test surfaced three surfaces still hardcoding "cursor declares no
modelConfigKey", broken by wiring review.models.cursor:

- tests/reviewer-config-federation.test.cjs: the #3691-narrows-#2797
  invariant test listed cursor among lanes that must own no model key.
- tests/settings-integrations.test.cjs: the #3651 keyless-lane test
  listed cursor as keyless, including a live config-set assertion that
  now correctly succeeds instead of failing (swapped to qwen).
- gsd-core/workflows/settings-integrations.md: the settable-keys
  enumeration and two prose call-outs still named cursor as keyless.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* chore(#3653): acknowledge deliberate growth of settings-integrations.md

settings-integrations.md grew 4 bytes because it now enumerates
review.models.cursor as a settable key alongside the other reviewer
lanes, matching the modelConfigKey wired for cursor in this PR.

Emitted-Drift-Ack-Growth: settings-integrations.md — adds review.models.cursor to the settable-keys enumeration and removes cursor from the two keyless-lane call-outs, matching #3653's modelConfigKey change

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* chore(#3653): fix malformed Emitted-Drift-Ack-Growth trailer

The previous commit's trailer was separated from Co-Authored-By by a
blank line, splitting it into an earlier, non-trailer paragraph — git's
trailer parser only recognizes the last contiguous block. Restating it
here immediately adjacent to Co-Authored-By so both parse as trailers.

Emitted-Drift-Ack-Growth: settings-integrations.md — adds review.models.cursor to the settable-keys enumeration and removes cursor from the two keyless-lane call-outs, matching #3653's modelConfigKey change
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

* docs(#3653): backfill changeset pr number

pr:0 -> pr:4160 now that https://github.com/open-gsd/gsd-core/pull/4160 exists.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

---------

Co-authored-by: sim <sim@local>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

src/review-lane-descriptor.cts

@@ -195,10 +195,11 @@ interface ReviewerLaneCommon {
    * config value that is not a positive finite number, falls back to `timeoutFloorMs` unchanged.
    * For a lane whose `args` template ALSO carries a native tool-side timeout (antigravity's
    * `--print-timeout`, via the `{{nativeTimeout}}` ARGV_PLACEHOLDER), the resolved value feeds both
-   * levels — see `resolveLanePlan`'s expansion of that token. Three lanes — `qwen`, `cursor`,
-   * `coderabbit` — accept neither a model flag nor a host and own no `review.timeouts.<slug>` key
-   * either, matching the same narrow key-ownership invariant `modelConfigKey` already follows for
-   * them (#3691 narrows #2797).
+   * levels — see `resolveLanePlan`'s expansion of that token. Two lanes — `qwen` and `coderabbit` —
+   * accept neither a model flag nor a host and own no `review.timeouts.<slug>` key either, matching
+   * the same narrow key-ownership invariant `modelConfigKey` already follows for them (#3691 narrows
+   * #2797). `cursor` gained a model flag (`review.models.cursor`, #3653) but still owns no
+   * `review.timeouts.cursor` key of its own.
    */
   timeoutConfigKey: string | null;
   emptyOutput: EmptyOutputPolicy;
@@ -431,10 +432,10 @@ export const REVIEWER_LANES: ReadonlyArray<ReviewerLane> = Object.freeze([
     probe: { kind: 'command-exists', binary: 'cursor-agent' },
     invoke: {
       binary: 'cursor-agent',
-      args: ['-p', '--mode', 'ask', '--trust', '--output-format', 'text', '{{prompt}}'],
+      args: ['-p', '{{model}}', '--mode', 'ask', '--trust', '--output-format', 'text', '{{prompt}}'],
       promptChannel: 'argv-file-ref',
       outputChannel: 'stdout',
-      modelArg: null,
+      modelArg: '--model',
       effortChannel: 'none',
     },
     timeoutFloorMs: 900_000,
@@ -444,7 +445,8 @@ export const REVIEWER_LANES: ReadonlyArray<ReviewerLane> = Object.freeze([
     evidenceClass: 'source-grounded',
     requiresBinaries: [],
     promptBudgetKey: 'review.max_prompt_tokens_per_reviewer.cursor',
-    modelConfigKey: null,
+    // #3653: cursor-agent exposes --model (204 selectable models); wired the same as codex.
+    modelConfigKey: 'review.models.cursor',
     handler: null,
   },
   {