feat(seer): Grant seer:write to Seer agent tokens by default (#127503)

## Summary
Grants the `seer:write` scope to Seer agents so that invocations of the
agent don't require `event:write` permission from the user to run any of
the autofix steps.

Previously the user would have to accept the permission from the seer
chat agent anytime they wanted to iterate on the auto fix generated plan
from the Seer chat panel. This allows the agent to now have the correct
scope so that it isn't required.

## Test plan
[x] Autofix iterations on RCA or Plan don't require a permission
acceptance.

Author: sebastianv1

src/sentry/seer/agent_token.py

@@ -93,6 +93,9 @@ def readonly_scopes() -> frozenset[str]:
     return frozenset(settings.SENTRY_READONLY_SCOPES)
 
 
+AGENT_DEFAULT_WRITE_SCOPES = frozenset({"seer:write"})
+
+
 def resolve_minting_principal(
     user: MintingUser, auth: AuthenticatedToken | None
 ) -> MintingPrincipal:
@@ -156,10 +159,14 @@ def compute_token_scopes(
     session_id: str,
     requested_scopes: Iterable[str] | None = None,
 ) -> list[str]:
-    """De-escalation rule: ``caller_scopes ∩ (read-only ∪ approved grants)``, optionally
-    narrowed by ``requested_scopes``. Never exceeds the caller's own authority."""
+    """De-escalation rule: ``caller_scopes ∩ (read-only ∪ default writes ∪ approved grants)``,
+    optionally narrowed by ``requested_scopes``. Never exceeds the caller's own authority."""
     caller = set(caller_scopes)
-    allowed = readonly_scopes() | active_grant_scopes(organization_id, user_id, session_id)
+    allowed = (
+        readonly_scopes()
+        | AGENT_DEFAULT_WRITE_SCOPES
+        | active_grant_scopes(organization_id, user_id, session_id)
+    )
     effective = caller & allowed
     if requested_scopes is not None:
         effective &= set(requested_scopes)

tests/sentry/seer/endpoints/test_group_ai_autofix.py

@@ -50,6 +50,9 @@
 
 USER_CONTEXT_MAX_LENGTH = 10000
 
+AGENT_TOKEN_SECRET = "test-seer-api-shared-secret-thirty-two-bytes!"
+AGENT_TOKEN_FLAG = "organizations:seer-agent-token-flow"
+
 
 def _user_context_length_calls(mock_distribution: Mock) -> list:
     return [
@@ -474,6 +477,55 @@ def test_post_triggers_autofix_agent(self, mock_trigger_explorer):
         assert response.data["run_id"] == 123
         mock_trigger_explorer.assert_called_once()
 
+    def _mint_agent_token(self) -> str:
+        self.login_as(user=self.user)
+        response = self.client.post(
+            f"/api/0/organizations/{self.organization.slug}/agent/token/",
+            data={"sessionId": "agent-session"},
+            format="json",
+        )
+        assert response.status_code == 200, response.content
+        return response.data["token"]
+
+    @override_settings(SEER_API_SHARED_SECRET=AGENT_TOKEN_SECRET)
+    @with_feature(AGENT_TOKEN_FLAG)
+    @patch("sentry.seer.endpoints.group_ai_autofix.trigger_autofix_agent")
+    def test_post_agent_token_runs_analysis_without_approval(self, mock_trigger_explorer):
+        group = self.create_group()
+        run = self.create_seer_run(organization=self.organization, seer_run_state_id=123)
+        mock_trigger_explorer.return_value = run
+        token = self._mint_agent_token()
+
+        response = self.client.post(
+            self._get_url(group.id),
+            data={"step": "root_cause"},
+            format="json",
+            HTTP_AUTHORIZATION=f"Bearer {token}",
+        )
+
+        assert response.status_code == 202, response.data
+        mock_trigger_explorer.assert_called_once()
+
+    @override_settings(SEER_API_SHARED_SECRET=AGENT_TOKEN_SECRET)
+    @with_feature(AGENT_TOKEN_FLAG)
+    @patch("sentry.seer.endpoints.group_ai_autofix.trigger_push_changes")
+    def test_post_agent_token_open_pr_requires_approval(self, mock_push_changes):
+        group = self.create_group()
+        token = self._mint_agent_token()
+
+        response = self.client.post(
+            self._get_url(group.id),
+            data={"step": "open_pr", "run_id": 123},
+            format="json",
+            HTTP_AUTHORIZATION=f"Bearer {token}",
+        )
+
+        assert response.status_code == 403, response.data
+        assert (
+            response["WWW-Authenticate"] == 'Bearer error="insufficient_scope", scope="event:write"'
+        )
+        mock_push_changes.assert_not_called()
+
     @patch("sentry.seer.endpoints.group_ai_autofix.trigger_push_changes")
     @patch("sentry.seer.endpoints.group_ai_autofix.trigger_autofix_agent")
     def test_post_seer_write_token_runs_analysis_but_cannot_open_pr(

tests/sentry/seer/endpoints/test_organization_agent_token.py

@@ -661,7 +661,7 @@ def _grant(self, *, organization=None, session_id="s1", scopes=("org:write",)):
             scope_list=list(scopes),
         )
 
-    def test_mint_defaults_to_readonly(self) -> None:
+    def test_mint_defaults_to_readonly_and_default_writes(self) -> None:
         self.login_as(self.owner)
         with self.feature(FLAG):
             resp = self._mint(sessionId="s1")
@@ -672,7 +672,11 @@ def test_mint_defaults_to_readonly(self) -> None:
         assert claims["org"] == self.org.id
         assert claims["sid"] == "s1"
         assert "org:write" not in claims["scopes"]
-        assert set(claims["scopes"]) <= agent_token.readonly_scopes()
+        assert "event:write" not in claims["scopes"]
+        assert "seer:write" in claims["scopes"]
+        assert set(claims["scopes"]) <= (
+            agent_token.readonly_scopes() | agent_token.AGENT_DEFAULT_WRITE_SCOPES
+        )
 
     def test_feature_off_is_not_found(self) -> None:
         self.login_as(self.owner)