Windows Host Paths

Windows host paths — the space in D:\GitHub Projects\… defeats naive parsers

On this host the repo lives at D:\GitHub Projects\recursive-harness — the path contains a space. Any tool or guard that splits a command/path on whitespace before honoring quotes truncates it to D:\GitHub and then acts on (or refuses) the wrong target. The failure is usually SILENT — a no-op or a misleading block, not a clear error — so it reads as "my command was wrong" when the real cause is the space. When an op you KNOW is valid is blocked or quietly does nothing on this checkout, suspect the space first, and fix it structurally — do not retry with a different quoting trick (it fails the same way).

Manifestation A — a leading env-var bypass token must be the FIRST token

HARNESS_TRUNK_LEASE_OK=1 (and similar guard-bypass prefixes) only register when the token is the literal leading token of the command. The guard regex allows ONLY preceding VAR=value assignments whose values contain no spaces. These silently defeat the bypass — the op stays BLOCKED with no new error:

• a leading cd … before the token,
• a multi-line script whose first line isn't the token,
• a preceding assignment to a space-containing path, e.g.

HARNESS="$(…)" → /d/GitHub Projects/recursive-harness or MAIN="D:/GitHub Projects/…" (the space breaks the regex's \S*).

Fix: lead with the bypass, inline the path, and never put cd or a space-valued VAR= before it:

HARNESS_TRUNK_LEASE_OK=1 git -C "/d/GitHub Projects/recursive-harness" worktree remove …

Use git -C "" (or os.chdir in Python) instead of a leading cd. If you need the harness path in a variable, set it AFTER the leading token, or hardcode the POSIX form in the command.

Manifestation B — PowerShell file-safety guard misfires → switch to Bash

A destructive PowerShell op (Remove-Item, Move-Item) on a legitimate path under the repo gets blocked as protected system path 'D:\GitHub' is blocked. The truncated D:\GitHub in that message is consistent with the built-in guard splitting the path at the space and matching the prefix against its protected-roots list — but this is the Claude Code built-in safety layer, not a harness hook, so the internal mechanism is INFERRED from the symptom, not reproduced. What IS established by outcome: retrying with different PowerShell quoting blocks AGAIN — it blocked twice in one session before switching shells worked.

Fix: use the Bash tool with a POSIX-quoted path instead:

f="/d/GitHub Projects/recursive-harness/cartograph/map.json"; rm -f "$f"

The Bash tool quotes the whole path as one argument, so the space never splits it.

Manifestation C — the harness's OWN guard has the same bug (locked)

hooks/guard_worktree_isolation.py has the same first-space truncation, pinned in the merged proposal to _expand_simple_vars (line 315): its assignment-value regex ([^\s;&|()]+) stops at the first space, so a $VAR holding this repo's path expands TRUNCATED into a phantom .claude/worktrees/ operand. The fix is enforcement-locked and tracked in proposals/resolved/P-2026-014-guard-worktree-space-split.md (human merges). Until it lands, expect worktree-path guard messages to show a truncated D:\GitHub.

Manifestation D — the user's shell is NOT my Bash tool

Rule 1 below ("prefer the Bash tool") is about the ASSISTANT's own tools, where Git Bash is on PATH. It is WRONG guidance the moment it's copied into a command handed to the user, or into a shipped script the user runs: their interactive shell is Windows PowerShell 5.1, where && is a parse error, a /d/… POSIX path resolves to D:\d\… (wrong), and a .sh shebang is ignored (silent no-op). bash itself may not even be on the user's PATH (this user hit CommandNotFoundException) — but DON'T rely on that as the failure mode: even when Git-for-Windows puts bash on PATH, those bash idioms still fail or run subtly wrong, so bash is unsafe to hand the user either way. Conflating "the Bash tool I have" with "the shell the user has" produced three dead invocations in a row before the user pushed back (session b46882f7).

Fix: anything the user will RUN ships as native PowerShell (.ps1), and any command you give the user must be valid PS 5.1 — never bash, &&, /d/… paths, or ./script.sh. Verify by RUNNING it in PS 5.1 (powershell -ExecutionPolicy Bypass -File …) before handing it over; do not assert an untested command works.

Manifestation E — PS 5.1 and pwsh 7 differ; test a .ps1 under BOTH

A .ps1 that passes under one runtime can break under the other. Two confirmed traps (both in the heal ledger):

• A non-ASCII char (e.g. em-dash —) in a UTF-8-no-BOM .ps1 is read as ANSI by PS

5.1 and cascades into Missing closing '}' parse errors — pwsh 7 reads UTF-8 and masks it. Keep harness .ps1 files ASCII-only; verify with a byte scan + Parser::ParseFile.

• Move-Item on a directory is an atomic rename under 5.1 but a non-atomic copy+delete

under pwsh 7, leaving a partial destination when the source is locked. Use [System.IO.Directory]::Move for atomic same-volume dir moves that fail cleanly.

Procedure that caught both: a test that runs the tool as a child process under BOTH powershell (5.1) AND pwsh (7), asserting pass in each (see tests/test-sync-account-sessions.ps1).

FALSE-GREEN trap (the tool is NOT the user's shell): the assistant's PowerShell tool runs pwsh 7+ (where &&, ternary, ?? work), but the user's interactive shell is 5.1 (where they fail). A green tool-side run is NOT proof a user-facing command works in 5.1 — write 5.1-safe syntax (; not &&), and to actually confirm, have the USER run it in their own session (the ! prefix runs a command inline there).

Manifestation F — native-Windows python/gh can't open a /d/… path passed as a string LITERAL

The Bash tool is Git Bash (MSYS). MSYS rewrites a /d/GitHub Projects/… POSIX path to D:\… only when it appears as a command-line ARGUMENT — it does NOT touch a path string that lives inside a program. So a native-Windows python/gh/node launched from the Bash tool receives the literal /d/… and fails — usually a bare FileNotFoundError that reads as "my path was wrong":

python -c "open('/d/GitHub Projects/recursive-harness/state/x.json')"
# FileNotFoundError — native python sees a literal /d/.. it can't resolve;
# MSYS converted nothing because the path was never an argv entry.

This is the inverse of Manifestation A/B: there, /d/… is the RIGHT form because the Bash tool quotes it as an argv arg; here the path is a string constant the child process reads verbatim, so MSYS never sees it. Hit twice during /retro 2026-06-26 (session_owners.json

• autonomy.json reads).

Fix: inside a program's string literals use a Windows path (D:/GitHub Projects/… — forward slashes are accepted by the Windows API and dodge backslash-escaping), OR keep the path OUT of the literal and hand it where MSYS DOES translate it — as an argv arg, via git -C "", or os.chdir(...). For a plain read, the Read tool sidesteps the shell entirely and never hits this.

Rules

• For the ASSISTANT's OWN file ops on this checkout, prefer the **Bash tool + POSIX

/d/GitHub Projects/… paths** over PowerShell — POSIX quoting survives the space cleanly. But anything the USER runs is PowerShell 5.1 (Manifestation D) — never hand them bash.

• Lead any guard-bypass env token; never precede it with cd or a space-valued

VAR= assignment. Use git -C/os.chdir, not cd.

• Quote EVERY path that touches the repo root, in every shell.
• A /d/… path inside a program's string LITERAL is NOT MSYS-translated (only argv

args are) — use D:/…, git -C/os.chdir, or the Read tool (Manifestation F).

• A block or no-op on a known-good path is a SPACE smell, not a you-were-wrong

smell. Don't re-quote-and-retry in the same shell — change the structure.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: GhostlyGawd
• Source: GhostlyGawd/recursive-harness
• License: MIT

Install and usage instructions live in the source repository linked above.