canary: detect provider API schema drift; release v0.7.0

The export reads ChatGPT's and Claude's undocumented internal web APIs,
which can change shape without notice; the worst failure for a backup tool
is a silent one (skipped/mis-parsed content with no error). Add a `canary`
command + BaseProvider.check_drift() (overridden by ChatGPT/Claude) that
fetches one listing page + one conversation per provider and asserts only
the normalizer's load-bearing fields — not the full response shape, which
churns harmlessly. The top silent risk it guards is a renamed retrieval-tool
author bypassing the hidden-content collapse. ERROR findings exit non-zero;
WARN findings are surfaced but non-fatal so a backup run is never blocked.

Also retires the in-app watch mode and headless StartOS direction from the
roadmap (tool stays a local, manually-run CLI) and updates docs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/providers/claude.py

@@ -16,7 +16,14 @@ from src.blocks import (
     make_unknown_block,
 )
 from src.loss_report import LossReport
-from src.providers.base import BaseProvider, ProviderError
+from src.providers.base import (
+    BaseProvider,
+    DRIFT_ERROR,
+    DRIFT_OK,
+    DRIFT_WARN,
+    ProviderError,
+    drift_finding,
+)
 
 logger = logging.getLogger(__name__)
 
@@ -232,6 +239,70 @@ class ClaudeProvider(BaseProvider):
             "messages": messages,
         }
 
+    def check_drift(self) -> list[dict]:
+        """Probe one listing page + one conversation; assert load-bearing fields.
+
+        See FUTURE.md §10. Real Claude messages are flat ``text``/``sender``;
+        the rich ``content`` block path is dormant, so its activation (content
+        becoming a list) is itself a drift event worth flagging. ``attachments``
+        / ``files`` are ignored by the normalizer — non-empty values are a
+        silent-loss risk.
+        """
+        findings: list[dict] = []
+        page = self.list_conversations(offset=0, limit=5)
+        if not page:
+            return [drift_finding(DRIFT_WARN, "listing",
+                                  "empty listing — cannot verify shape")]
+
+        item = page[0]
+        if not (item.get("uuid") or item.get("id")):
+            findings.append(drift_finding(DRIFT_ERROR, "listing", "summary missing uuid/id"))
+        if not (item.get("name") or item.get("title")):
+            findings.append(drift_finding(DRIFT_WARN, "listing", "no name/title on summary"))
+        if not (item.get("updated_at") or item.get("update_time")):
+            findings.append(drift_finding(DRIFT_WARN, "listing", "no updated_at on summary"))
+
+        conv_id = item.get("uuid") or item.get("id")
+        if not conv_id:
+            return findings or [drift_finding(DRIFT_ERROR, "listing", "no id to fetch")]
+        raw = self.get_conversation(conv_id)
+        if not (raw.get("uuid") or raw.get("id")):
+            findings.append(drift_finding(DRIFT_ERROR, "detail", "no uuid/id on detail"))
+        msgs = raw.get("chat_messages") or raw.get("messages")
+        if not isinstance(msgs, list) or not msgs:
+            findings.append(drift_finding(
+                DRIFT_ERROR, "detail", "chat_messages missing/empty — 0 messages"))
+            return findings
+
+        saw_sender = saw_text = False
+        flagged_list = flagged_attach = False
+        for m in msgs:
+            if m.get("sender") or m.get("role"):
+                saw_sender = True
+            content = m.get("content")
+            if isinstance(content, list) and not flagged_list:
+                findings.append(drift_finding(
+                    DRIFT_WARN, "content",
+                    "message.content is now a LIST — Claude switched to typed blocks; "
+                    "the dormant _dispatch_claude_block path is now live, verify rendering"))
+                flagged_list = True
+            if m.get("text") or content:
+                saw_text = True
+            if (m.get("attachments") or m.get("files")) and not flagged_attach:
+                findings.append(drift_finding(
+                    DRIFT_WARN, "attachments",
+                    "message has non-empty attachments/files — the normalizer ignores "
+                    "these (silent loss); add handling"))
+                flagged_attach = True
+
+        if not saw_sender:
+            findings.append(drift_finding(DRIFT_ERROR, "messages", "no sender/role on any message"))
+        if not saw_text:
+            findings.append(drift_finding(DRIFT_WARN, "messages", "no text/content found"))
+        if not findings:
+            findings.append(drift_finding(DRIFT_OK, "schema", "all load-bearing fields present"))
+        return findings
+
 
 # ---------------------------------------------------------------------------
 # Internal helpers