respawns can actually warm
claude-code's --resume <session_id> requires either:
a) a deferred-tool marker in the resumed session (i.e. the prior
session paused mid-tool-call), or
b) a non-empty -p prompt to continue the conversation with.
Watchdog-killed sessions have neither: the kill is asynchronous and
leaves no deferred-tool marker, and our harness was passing an empty
-p (because `resume_context_owned` is None for the common respawn
case). claude-code then aborts with:
"Error: No deferred tool marker found in the resumed session.
Either the session was not deferred, the marker is stale (tool
already ran), or it exceeds the tail-scan window. Provide a
prompt to continue the conversation."
The harness sees an aborted CLI with no session, prunes the recorded
session_id, and respawns cold — paying the full prompt-cache miss for
EVERY respawn. The new session_store logging (commit 0b50a624) made
this 100% legible: every warm spawn we observed went `mode=warm` →
crash → prune → `mode=cold` within a couple of seconds.
Fix: when resuming with no failure-context to send, default the -p
prompt to a brief "continue from PLAN.md" line. claude-code now has a
valid continuation message and warm-resume should actually work.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dave
bd517f2857