--share and --resume flags together overwrite the original session.md instead of appending

[huntj88]

Describe the bug

--share and --resume flags together overwrite the original session.md instead of appending

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Run 1

copilot --share --no-color -p "count to 100"

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2
3
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5
6
7
8
9
10
.... (truncated for sharing issue)
100

Total usage est: 1 Premium request
API time spent: 11s
Total session time: 16s
Total code changes: +0 -0
Breakdown by AI model:
gpt-5.3-codex 17.4k in, 613 out, 8.8k cached (Est. 1 Premium request)
Session exported to: copilot-session-ac4570b4-6bfd-474e-b69c-1f5befb3e01a.md

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Run 2 with --resume

copilot --share --no-color --resume ac4570b4-6bfd-474e-b69c-1f5befb3e01a -p "count to 200"

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2
3
4
5
6
7
8
9
10
.... (truncated for sharing issue)
200

Total usage est: 1 Premium request
API time spent: 8s
Total session time: 1m 27s
Total code changes: +0 -0
Breakdown by AI model:
gpt-5.3-codex 17.7k in, 562 out, 8.8k cached (Est. 1 Premium request)
Session exported to: copilot-session-ac4570b4-6bfd-474e-b69c-1f5befb3e01a.md

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Share session output

🤖 Copilot CLI Session

Session ID: ac4570b4-6bfd-474e-b69c-1f5befb3e01a
Started: 2/24/2026, 7:53:47 AM
Duration: 11s
Exported: 2/24/2026, 7:53:58 AM

_{⏱️ 2s}

👤 User

count to 200

---

_{⏱️ 11s}

💬 Copilot

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2
3
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5
6
7
8
9
10
.... (truncated for sharing issue)
200

---

_{Generated by GitHub Copilot CLI}

Affected version

GitHub Copilot CLI 0.0.415

Steps to reproduce the behavior

use --share with --resume flags

Expected behavior

Append instead of overwrite

Additional context

No response