claude -c / --continue does not preserve --model from prior session

Version

2.1.138 (also reproduced in earlier 2.1.x)

Summary

claude -c / claude --continue resumes a session's conversation history but silently drops the model setting, reverting to the account default.

Steps to reproduce

1. Start a session with a non-default model:

``
cd ~/some-project
claude --model haiku-4-5
``

1. Send a few prompts and get responses.
2. /exit
3. From the same cwd, run claude -c

Expected

Continuing the session restores the session config — including the model — exactly as it was. (Conversation continuity should imply model continuity.)

Actual

Conversation history resumes correctly, but the model silently reverts to the account's default (e.g. opus on Max plan). The user only notices indirectly via response style, latency, or cost changes.

Why it matters

Any tooling that batch-restarts sessions (e.g. across a claude update) loses per-session model config silently. The fix should be cheap: the model is already recorded per-message in the JSONL transcript, so it could be inferred at resume time.

Workaround

Pass --model <name> explicitly when continuing:

claude -c --model haiku-4-5

But this requires the user / tooling to know what model the prior session was on, which is awkward.