Move a Coding-Agent Session from Mac to Windows

What this guide proves—and what it does not

This is an operator workflow for moving one supported, vendor-native session from macOS to native Windows 11 through Reinstate v0.1.0-rc.8. It uses the same commands and stop conditions as the repository’s Phase 1 Mac/Windows acceptance runbook, but completing it on personal devices is not release certification.

Reinstate transfers an age-encrypted snapshot and known structural project paths. Git remains responsible for source code and working-tree state. Claude Code or Codex CLI remains responsible for native resume.

Concern	macOS source	Reinstate	Windows destination
Repository checkout	Existing Mac path	Maps it to a canonical project ID	Existing Windows path
Session selection	Human chooses one ID	Discovers and snapshots that ID	Restores the same vendor ID
Encryption	Passphrase entered locally	Encrypts before upload	Decrypts after download
Credentials	Stored in macOS Keychain	Stores only a credential reference in config	Stored in Windows Credential Manager
Resume	Source vendor writes the session	Does not execute the agent	Same vendor resumes natively

Key points

• Use one stable project ID on both devices even though paths such as /Users/me/Code/app and C:\src\app differ.
• Use native Windows PowerShell for this workflow. WSL2 is a separate Linux Reinstate device with different path semantics; WSL1 is unsupported.
• Choose exactly one claude or codex session and preview both transfer directions with --dry-run.
• Resume remains same-vendor: Claude Code to Claude Code, or Codex CLI to Codex CLI. RC8 does not convert one vendor’s transcript into the other vendor’s native format.
• Credentials, vendor authentication, API keys, OAuth material, .env files, Git state, MCP servers, skills, plugins, and hooks do not move with the session.
• Keep independent backups. The encrypted remote profile is a continuity artifact, not a replacement for repository backups or a tested retention plan.
• Native Windows, macOS amd64, WSL2, and physical two-device acceptance still contain open release gates. Do not describe a personal success as stable Phase 1 certification.

Before you begin

Use a harmless session in a disposable or non-sensitive repository first. Confirm that moving its contents to the selected bucket and Windows computer is permitted by employer, client, data-residency, and device policies.

Configure a private provider bucket before this guide. Use either the Amazon S3 storage guide or the Cloudflare R2 storage guide. Never paste the storage secret, encryption passphrase, transcript, or downloaded snapshot into a coding-agent prompt, shell argument, commit, screenshot, or test report.

Platform and release qualifications

Environment	Current qualification
macOS native arm64	Current source compatibility evidence covers the documented Claude Code and Codex ranges; a real second device is still required for transfer evidence.
macOS native amd64	A required stable-release row that remains open.
Windows 11 native amd64	A primary Phase 1 target whose native installer, restore, and resume acceptance gate remains open until recorded evidence passes.
WSL2 amd64	Installer-compatible and documented for smoke testing, but it is not native Windows and its Phase 1 gate remains open.
Linux native	Installer-compatible, but not a certified Phase 1 agent-resume target.
WSL1	Unsupported.

Current RC8 source evidence recognizes Claude Code 2.1.219–2.1.220 and Codex CLI 0.133.0–0.145.0. A result outside those inclusive ranges is UNTESTED; rein setup check exits with compatibility code 5 and mutating push or pull is blocked.

Native Windows and WSL are different devices

Do not point native Windows and WSL at one shared agent-state directory or one Reinstate home:

Property	Native Windows	WSL2
Shell	PowerShell	Linux shell
Default Reinstate home	%USERPROFILE%\.reinstate	~/.reinstate inside WSL
Paths	C:\src\app	/home/me/app or /mnt/c/src/app
Phase 1 role in this guide	Destination	Out of scope

If the agent runs inside WSL, follow a separately configured Linux/WSL workflow; do not label it native Windows evidence.

Command placeholders and parameters

Placeholder or flag	Meaning
AGENT	Replace with exactly claude or codex, and use the same value on both devices.
SESSION_ID	The exact harmless source ID returned by rein list --agent AGENT.
PROFILE_ID	The non-secret UUID printed by first-device rein init; copy it exactly to Windows.
PROJECT_ID	A stable ID such as github.com/acme/app, identical on both devices.
MAC_PROJECT	The absolute macOS checkout path, such as /Users/me/Code/app.
$WindowsProject	A PowerShell variable containing the absolute native Windows checkout path.
STORAGE_ENDPOINT	The S3-compatible service endpoint, without the bucket name.
STORAGE_REGION	The provider signing Region; use auto for Cloudflare R2.
STORAGE_BUCKET	The private bucket name only.
--profile-id PROFILE_ID	Joins the existing encrypted remote profile instead of generating an unrelated one.
--session SESSION_ID	Limits transfer to the one selected session.
--dry-run	Reads, authenticates, validates, and plans without writing a remote snapshot or local session.

1. Verify the two native environments

Install RC8 on the Mac:

curl -fsSL https://reinstate.dev/install.sh | sh
rein version --json
sw_vers
uname -m

Install RC8 from native Windows PowerShell, not a WSL shell:

irm https://reinstate.dev/install.ps1 | iex
rein version --json
Get-ComputerInfo |
  Select-Object WindowsProductName, WindowsVersion, OsBuildNumber
[Environment]::Is64BitOperatingSystem

Run claude --version or codex --version on both computers for the one vendor being moved. Clone or update the repository through Git, then record the two absolute checkout paths. Ensure the Windows path is a native path and not a WSL mount.

Do not transfer a session while either checkout is on an unexpected branch, commit, or unreviewed dirty working tree. RC8 maps structural paths; it does not synchronize Git state or prove environment equivalence.

Expected result: both rein version --json commands report 0.1.0-rc.8, the Mac and 64-bit native Windows environments are identified separately, the same agent vendor is installed in a recognized range, and the same repository exists at two recorded absolute paths.

2. Initialize and verify the Mac profile

Replace every placeholder, then run this from a private Mac terminal:

rein init \
  --endpoint STORAGE_ENDPOINT \
  --region STORAGE_REGION \
  --bucket STORAGE_BUCKET \
  --project "PROJECT_ID=MAC_PROJECT"

Enter the storage access-key ID and secret access key only through the two hidden prompts. Initialization does not request or store the encryption passphrase. RC8 creates a profile UUID, writes and deletes a two-byte storage probe, stores the credential in the OS keyring, and saves config.toml plus state.json only after the probe succeeds.

Record only the printed non-secret profile_id, then run:

rein setup check
rein doctor --self-test

Stop if the selected adapter is not SUPPORTED, the self-test fails, or the project mapping does not resolve to the intended Mac checkout. Do not use an unsafe compatibility override; RC8 has none.

Expected result: init prints initialized reinstate home (config.toml + state.json) and profile_id=<UUID>, setup and self-test exit 0, and the temporary storage probe is gone. No persistent manifest.age exists until the first successful push.

3. Preview and push one selected session

Close the Mac agent cleanly and choose one harmless session:

rein list --agent AGENT
rein push --agent AGENT --session SESSION_ID --dry-run
rein push --agent AGENT --session SESSION_ID
rein status

Enter the long encryption passphrase only at Reinstate’s hidden prompt and store it in a password manager. You will need the exact same passphrase on Windows. Do not use --all for the first transfer.

The dry-run must identify one snapshot without mutation. The real push encrypts the snapshot locally, writes the encrypted snapshot and manifest beneath profiles/PROFILE_ID/, and updates local synchronization state.

Expected result: dry-run begins with would push 1 snapshot(s) and dry_run=true; the real command reports pushed 1 snapshot(s) and dry_run=false; status reports one remote revision; and the private bucket contains manifest.age plus an opaque snapshots/<id>.age, not a plaintext transcript or credential file.

4. Join the profile on native Windows

In native Windows PowerShell, set a local variable to the real checkout:

$WindowsProject = "C:\absolute\path\to\project"

Initialize the second device with the exact first-device profile UUID:

rein init `
  --profile-id PROFILE_ID `
  --endpoint STORAGE_ENDPOINT `
  --region STORAGE_REGION `
  --bucket STORAGE_BUCKET `
  --project "PROJECT_ID=$WindowsProject"

Enter the same storage credential through hidden prompts. Additional-device init requires the existing encrypted manifest.age before it saves local configuration; a wrong profile ID, endpoint, Region, bucket, prefix, or credential fails closed.

Then validate the native destination:

rein setup check
rein doctor --self-test
rein status

rein status asks for the encryption passphrase. A deliberately wrong phrase must produce a decryption/authentication failure without restoring a session, changing an agent file, or creating a backup. Retry with the correct phrase.

Expected result: second-device init reuses PROFILE_ID, setup and self-test exit 0, status with the correct passphrase reports the selected remote session, and the project mapping resolves PROJECT_ID to the intended native Windows path without creating any agent session file yet.

5. Preview, pull, and resume on Windows

Close every process for the selected agent. Preview the exact destination and backup root:

rein pull --agent AGENT --session SESSION_ID --dry-run
rein pull --agent AGENT --session SESSION_ID
rein list --agent AGENT
Get-ChildItem -Recurse `
  (Join-Path $env:USERPROFILE ".reinstate\backups") |
  Select-Object -First 20 FullName

The dry-run should say would pull, name the native vendor destination, and show the backup root without mutation. The real pull validates and decrypts the complete artifact before writing, backs up an existing destination when one exists, writes through a private temporary sibling, and atomically renames the restored file.

Resume through the same native vendor:

claude --resume SESSION_ID

or:

codex resume SESSION_ID

Verify visually that this is the intended prior session and that it opens from the mapped Windows project. Do not copy transcript content into public evidence.

Expected result: dry-run reports would pull 1 snapshot(s) with dry_run=true; the real command reports pulled 1 snapshot(s) with dry_run=false; the exact ID is discoverable at its native Windows path; an existing target has a timestamped backup; and the same-vendor CLI resumes it without a structural path error.

How path remapping works

The two local paths map to one portable identity:

Device	Local configuration	Portable structural form
Mac	PROJECT_ID=/Users/me/Code/app	${REPO:PROJECT_ID}/...
Windows	PROJECT_ID=C:\src\app	${REPO:PROJECT_ID}/...

The Claude Code adapter recomputes the destination project-directory key from the Windows root. The Codex adapter rewrites the known structural session_meta.cwd field and preserves Codex’s native date-partitioned rollout layout. Reinstate does not blindly replace path-shaped text inside prompts, responses, shell output, or unknown vendor fields.

Path remapping also does not install runtimes, recreate environment variables, move uncommitted code, align Git branches, copy agent authentication, or synchronize MCP servers and skills.

Visible evidence to retain

Record a private, redacted result containing:

• OS versions and architectures;
• Reinstate and agent versions;
• the non-secret profile UUID and session ID;
• canonical project ID plus redacted source and destination paths;
• command exit codes and would push, pushed, would pull, and pulled counts;
• remote object names and a boolean that selected plaintext markers were absent from a privately downloaded .age object;
• whether an existing target received a timestamped backup; and
• whether the vendor-native resume opened the intended session.

Never retain the passphrase, storage secret, transcript text, downloaded snapshot, or unredacted sensitive paths as evidence.

Failure modes and common errors

What does pre-init config missing (exit 3) mean?

Meaning: The Reinstate home is intentionally unconfigured.

Safe recovery: Run the reviewed init command; do not treat this expected pre-init failure as a pass.

What should I do after compatibility exit 5 or UNTESTED?

Meaning: The agent version or layout lacks release evidence.

Safe recovery: Stop mutation and use the compatibility page to choose a recognized version.

Why does Windows report remote profile manifest not found?

Meaning: Windows used the wrong profile or storage coordinates, or the Mac has not pushed yet.

Safe recovery: Confirm the Mac push, then copy the exact profile UUID, endpoint, Region, bucket, and prefix. Never create a substitute empty profile.

What should I do after a decryption or authentication failure?

Meaning: The passphrase is wrong or ciphertext is damaged.

Safe recovery: Stop, verify the passphrase privately, preserve remote and local copies, and retry without changing session files.

Why does pull report remote session not found (exit 2)?

Meaning: AGENT or SESSION_ID does not match the selected remote entry.

Safe recovery: Recheck Mac metadata and rein status; do not broaden the pull to --all.

What should I do after safety exit 7?

Meaning: The destination agent appears active and an existing target could be overwritten.

Safe recovery: Close the same-vendor agent completely and rerun the dry-run; do not bypass the refusal.

What should I do after conflict exit 6?

Meaning: The Windows-local and remote copies diverged.

Safe recovery: Preserve both, then inspect rein conflicts list and rein conflicts show CONFLICT_ID; use --keep-both when neither branch may be lost.

Why does resume open from the wrong project?

Meaning: The canonical ID or Windows mapping is wrong.

Safe recovery: Stop the agent, preserve the restored file and backup, correct configuration through a reviewed re-init, and pull again only after previewing the destination.

Safe rollback and undo

Reinstate RC8 does not provide a general rein undo or remote-session delete command.

1. A push or pull --dry-run mutates neither remote session state nor local vendor files.
2. A failed first-device init does not save config or state after a failed storage probe.
3. A failed additional-device init does not save config when the existing remote manifest cannot be verified.
4. A wrong-passphrase pull fails before restore and creates no backup.
5. If a real pull replaced an existing target, stop the agent and preserve both the restored file and the timestamped copy under %USERPROFILE%\.reinstate\backups\ before deciding which one to keep.
6. If local and remote state diverged, do not delete conflict metadata. Inspect it and resolve explicitly with --keep-local, --keep-remote, or --keep-both.
7. Remote cleanup is a provider operation. Stop all participating devices, retain needed independent backups, verify the exact profiles/PROFILE_ID/ target, and revoke the dedicated credential after approved deletion.

Never delete only manifest.age while leaving snapshots behind. A second device requires that encrypted manifest and will fail closed if it disappears.

Verification checklist

• Both machines report RC8, native OS identity, and a recognized version of the same agent vendor.
• The repository exists on both machines, and one canonical project ID maps to the two reviewed absolute paths.
• Mac setup and self-test pass; the remote profile did not exist before the first successful selected-session push.
• Push and pull dry-runs each select exactly AGENT:SESSION_ID and show no mutation.
• The bucket contains only encrypted manifest.age and .age snapshot objects under the recorded profile prefix; credentials are absent.
• Windows second-device init reuses the exact Mac profile UUID and verifies the existing manifest before saving config.
• The pull reports the intended native destination and backup root, and an existing target is backed up before replacement.
• Claude Code or Codex resumes its own session ID from the mapped Windows project without a structural path error.
• No claim says the repository’s still-open physical two-device acceptance matrix passed merely because this personal workflow succeeded.

Current limitations

• RC8 is explicit push/pull synchronization, not background automatic sync.
• It moves complete immutable snapshots rather than deltas and has no remote retention or garbage-collection policy.
• Native resume is same-vendor only. Portable handoffs between vendors are a later phase.
• Path mapping covers known structural fields, not prose, tool output, or arbitrary strings that resemble paths.
• Git state, build tools, shells, environment variables, agent authentication, MCP servers, skills, plugins, hooks, and settings remain device-local.
• WSL2 is a separate installer-compatible environment with its own Linux paths and home; it is not the native Windows destination in this guide.
• Native Windows, macOS amd64, WSL2 smoke, and physical device results remain open gates for stable Phase 1. This guide is operational documentation, not a certified Phase 1 agent-resume target result.
• Reinstate’s encryption protects remote confidentiality, but it cannot protect a compromised endpoint or recover a lost passphrase.

Mac-to-Windows session FAQ

Does the Mac need to stay online after the push?

No. After the selected push succeeds, native Windows downloads from your S3-compatible bucket. The Mac can be offline, but Windows still needs network access to the bucket and the same passphrase.

Can I use WSL instead of native Windows?

Not for the workflow described here. WSL2 can be configured as a separate Linux Reinstate device with its own paths, home, agent installation, and acceptance status. WSL1 and shared native/WSL agent-state folders are unsupported.

Can I move a Claude Code session into Codex?

No. RC8 restores Claude Code state for Claude Code and Codex state for Codex CLI. It does not silently reconstruct one vendor’s native transcript format for another vendor.

What if the checkout paths are different?

That is the intended case. Map the same canonical PROJECT_ID to the Mac path on the source and the Windows path on the destination. Reinstate normalizes known structural fields during snapshot creation and expands them through the destination mapping during restore.

Why did pull refuse while the agent was open?

When an existing destination may be replaced, RC8 checks whether that vendor process is active. Safety exit 7 protects the live agent file. Close the agent fully, rerun the dry-run, confirm the destination and backup root, and then pull.

Is the encrypted bucket a complete backup?

No. It is a user-owned continuity store for supported session artifacts. Maintain independent backups of repositories and any session history your policy requires, preserve restore-tested copies, and remember that losing the passphrase makes remote ciphertext unrecoverable by design.