feat(web): send Hermes identity headers on Perplexity requests

Add HTTP-Referer, X-Title, User-Agent (HermesAgent/<version>) and
X-Pplx-Integration: hermes-agent to the Perplexity web provider's
/search and /sdk/content/snippets requests. Same static headers Hermes
already sends Kimi and OpenCode; nothing per-user, no extra requests.

plugins/web/perplexity/provider.py

@@ -40,12 +40,24 @@ from urllib.parse import urlparse
 import httpx
 
 from agent.web_search_provider import WebSearchProvider
+from hermes_cli import __version__ as _HERMES_VERSION
 
 logger = logging.getLogger(__name__)
 
 _DEFAULT_BASE_URL = "https://api.perplexity.ai"
 _KEY_URL = "https://www.perplexity.ai/account/api"
 
+# Identify Hermes to Perplexity: the same static harness identity Hermes sends Kimi and
+# OpenCode, plus Perplexity's integration header. No per-user identifier and no separate
+# request; the call already carries the user's own API key.
+_HEADERS = {
+    "HTTP-Referer": "https://hermes-agent.nousresearch.com",
+    "X-Title": "Hermes Agent",
+    "User-Agent": f"HermesAgent/{_HERMES_VERSION}",
+    "X-Pplx-Integration": "hermes-agent",
+}
+
+
 # Search API hard cap for search_type=web.
 _MAX_SEARCH_RESULTS = 20
 # Snippet budgets (backend limits: max_tokens 1-16384, per page 1-4096).
@@ -80,6 +92,7 @@ def _perplexity_request(endpoint: str, payload: Dict[str, Any]) -> Dict[str, Any
         headers={
             "Authorization": f"Bearer {api_key}",
             "Content-Type": "application/json",
+            **_HEADERS,
         },
     )
     if response.status_code >= 400:

tests/tools/test_web_tools_perplexity.py

@@ -16,6 +16,17 @@ def _ok(payload):
     return resp
 
 
+def _assert_hermes_identity_headers(headers):
+    """Both Perplexity endpoints carry the Hermes identity headers (same set as Kimi/OpenCode)
+    plus Perplexity's integration header."""
+    from hermes_cli import __version__
+
+    assert headers["HTTP-Referer"] == "https://hermes-agent.nousresearch.com"
+    assert headers["X-Title"] == "Hermes Agent"
+    assert headers["User-Agent"] == f"HermesAgent/{__version__}"
+    assert headers["X-Pplx-Integration"] == "hermes-agent"
+
+
 def test_search_dispatch_maps_search_api_shape():
     """web_search on backend=perplexity hits /search with Bearer auth and maps snippet→description."""
     import tools.web_tools as wt
@@ -35,6 +46,7 @@ def test_search_dispatch_maps_search_api_shape():
 
     assert post.call_args.args[0] == "https://api.perplexity.ai/search"
     assert post.call_args.kwargs["headers"]["Authorization"] == "Bearer pplx-test"
+    _assert_hermes_identity_headers(post.call_args.kwargs["headers"])
     body = post.call_args.kwargs["json"]
     assert body["query"] == "bloom filter"
     assert 1 <= body["max_results"] <= 20  # dispatcher bucket-rounds the fetch limit
@@ -65,6 +77,7 @@ def test_extract_dispatch_snippets_per_url_and_missing_key():
         out = json.loads(asyncio.run(wt.web_extract_tool(urls)))
 
     assert post.call_args.args[0] == "https://api.perplexity.ai/sdk/content/snippets"
+    _assert_hermes_identity_headers(post.call_args.kwargs["headers"])
     body = post.call_args.kwargs["json"]
     assert body["urls"] == urls
     assert body["query"] == "tokio tutorial smol"