# Identifying A Deployed Build (Operator Runbook)

> **Written 2026-08-11 after a false alarm.** An investigation treated the windev production
> binary as having no traceable provenance, on two pieces of evidence that both turned out to be
> normal output of our own build and deploy procedure. The binary was fine. This runbook records
> what those signals actually mean, so the next person spends minutes rather than a forensics pass.

## The version stamp is unreliable on Windows builds from 2026-07-09 to 2026-08-10

`src/Directory.Build.props` appends the git short SHA to `InformationalVersion` (`0.1.2+<sha>`) so a
running binary can be mapped back to a commit. That stamping was introduced by `ec6f82b`
(2026-07-09, TST-11) and was **broken on Windows for its first month**.

`$(MSBuildThisFileDirectory)` ends in a path separator. On Windows that trailing backslash escaped
the closing quote of the `Exec` command, so `git rev-parse` never ran correctly; because the target
runs with `ContinueOnError` and `ConsoleToMSBuild` (which mixes stderr into `ConsoleOutput`), git's
failure text was stamped as the source revision. The observed form is:

```
0.1.2+fatal: cannot change to ...
```

The full string recovered from wonder's 2026-08-09 server binary (read 2026-08-12) shows the whole
failure, including the mismatched `'` … `"` that caused it:

```
0.1.2+fatal: cannot change to 'C:\build\mxgw-deploy\src" rev-parse --short HEAD': Invalid argument
```

**Do not read the leading `0.1.2` as provenance.** It is the static base `<Version>` every build
carries, not a truncated SHA. The hazard is a false positive rather than a blank: `0.1.2+fatal:…`
reads like a version that succeeded and then picked up noise, when in fact there is no usable
identity anywhere in the string. For a binary built in this window the commit is **not recoverable
from the binary at all** — so finding nothing is the expected result, not evidence against a SHA
established another way.

`0152180` (2026-08-10 05:49, merged in `c46e5bb`) fixed it two ways: the quoted path gained a
trailing `.` so the separator can no longer escape the quote, and `SourceRevisionId` is now gated on
a short-SHA shape so no future git failure text can become the revision either.

**What this means for an operator.** A git error string in the version of a binary built on Windows
in that window is the *expected* result of our own build. It is non-diagnostic in **both**
directions — it neither incriminates a build nor confirms one, so it should not be treated as
evidence of anything. macOS builds in the same window stamp correctly, as do all builds after
`0152180`.

## An absent `C:\build\mxgw-deploy` is expected

The deploy procedure builds from a **detached worktree** (`git worktree add C:\build\mxgw-deploy
<sha>`) so the host's own checkout, which usually sits on a feature branch, is not disturbed. The
worktree is removed once the publish is copied out. Finding that the directory a binary was built
from no longer exists is the normal end state of a correct deploy, not a deleted trail.

## What does identify a build

In rough order of cost:

1. **Behaviour over the wire.** Works against a running service, needs no host access, and is the
   fastest discriminator for the worker. `53f69cd` correlates `OnWriteComplete` onto **plain**
   `Write`/`Write2` replies; `b948e69` did so only for `WriteSecured`/`WriteSecured2`. So a plain
   `Write` whose reply carries `statuses[0]` proves the worker is at or past `53f69cd`, and an empty
   `statuses` proves it is not. Keep it non-destructive by writing to a read-only tag — the refusal
   still exercises the path and returns `OPERATIONAL_ERROR` with detail `1007`.
2. **PDB source hashes.** Slower, needs the deployed symbols, but independent of anything the build
   stamped. **Do not read this as *the* technique on its own.** What settled the 2026-08-11
   investigation was two independent derivations agreeing: a PDB source-hash match, and a
   contemporaneous deploy record written the same evening that named the same two commits. The
   convergence is the result's strength, not either method alone — a hash match tells you which
   sources a binary was built from, but not that the build was intentional or which host it went to.
   A reader with only one of the two available should weight it accordingly and look for a second
   line of evidence.
3. **Deployment-side naming.** Since 2026-08-07 the server deploys to a dated directory
   (`Server-YYYYMMDD`) with the NSSM `Application`/`AppDirectory` repointed at it, and backup
   directories carry operator-chosen labels naming the work (for example
   `Worker.bak-20260809-planwrites`). Those conventions place a build in time and intent, and an
   accidental or off-book deploy tends not to follow them.

4. **The host's own backup directories, read as a chain.** Each `Server.bak.<timestamp>` holds the
   exe that deploy *replaced*, so a sweep of `VersionInfo` across them reconstructs the host's deploy
   history from the host itself, with no repo access and no deploy record. A backup stamped
   `20260811T060739` containing an exe written 2026-08-09 is the 08-09 build being displaced — the
   backup's timestamp dates the *next* deploy, not the build inside it. Reading a file's version is
   non-destructive, unlike opening a SQLite store in a backup directory, which mutates it. This is
   what established that wonder's `b948e69` and `0a9715d` were two deploys two days apart rather
   than two competing claims about one binary.

Note that **mixed Server and Worker SHAs are deliberate**, not drift: the two are swapped
independently whenever the contracts are wire-identical, so a host legitimately runs one commit for
the server and a later one for the worker.

## Recorded deploys

| Date | Host | Server | Worker |
|---|---|---|---|
| 2026-08-09 | windev (`10.100.0.48`) | `b948e69` (`Server-20260809`) | `53f69cd` |
| 2026-08-09 | `wonder-app-vd03` | `b948e69` | `53f69cd` |
| 2026-08-11 | `wonder-app-vd03` | `0a9715d` (this deploy wrote `Server.bak.20260811T060739`, holding the displaced 08-09 build) | *carried forward* |
| 2026-08-12 | `wonder-app-vd03` | `55f2889` (this deploy wrote `Server.bak.20260812T040122`, holding `0a9715d`) | *carried forward* |

The two wonder rows after 08-09 are **server swaps**; their worker cells are carried forward from the
08-09 entry rather than re-verified, so treat the worker SHA there as unconfirmed. Their server SHAs
come from the backup-chain read described above (technique 4), except `55f2889`, which was read
directly from the live exe's stamp — trustworthy because it postdates `0152180`.

`b948e69` is **confirmed by PDB source-hash match plus the contemporaneous record, never by a version
stamp** — that build falls in the broken-stamp window and its stamp is structurally unavailable (see
the first section). `0a9715d` is the first wonder build to stamp cleanly, since `0152180` landed
before it.

The 2026-08-09 deploy was **two separate swaps**, which is why a single build time does not describe
it: the 2026-08-11 investigation dated the server file write to 19:20:24 and the worker to 19:50:06,
the latter two minutes after `53f69cd` merged at 19:48, with a matching service stop/start at
19:50:29/34.

That reading is confirmable from artifacts still on disk, without trusting the narrative: windev
carries **two** worker backup directories from that day (`Worker.bak-20260809` and
`Worker.bak-20260809-planwrites`), and wonder carries `Worker.bak.20260809-planwrites`. Two backups
because there were two worker operations. This is easy to misread as redundancy — it is the second
swap's fingerprint.

## The 2026-08-09 deploy returned the worker to mainline

Worth stating because it went unrecorded at the time and later read as a mystery rather than as the
improvement it was. Before that deploy, production ran worker `dd7ca163` (2026-05-22), which is
contained **only** by `origin/test/client-e2e-coverage` and is not an ancestor of `main` — meaning
the x86 worker in production could not be rebuilt from any mainline commit. `53f69cd` is on `main`,
which closes that. Verified 2026-08-11 with `git merge-base --is-ancestor`.

## Related Documentation

- [Diagnostics](../Diagnostics.md)
- [Gateway Configuration](../GatewayConfiguration.md)
