fix(openrfid): fix review issues from PR #306 (PIDFILE, stray echo, help_url, error handling)

[kbaker827]

Summary

Bug fixes for the OpenRFID overlay introduced in #306, addressing issues found during review.

• Wrong PIDFILE path in S99openrfid — The init script used /var/run/filament-detect.pid, a leftover from the previous service name. This has been corrected to /var/run/openrfid.pid. As written, if any remnant PID file from the old filament-detect service existed, the already-running guard would fire incorrectly and OpenRFID would silently refuse to start.

• Stray echo in 15_settings_openrfid.yaml — The openrfid-generic activation command ended with echo Please read the relevant documentation.... This was redundant (the confirm dialog already shows this message before the user proceeds) and was explicitly flagged for removal in the review thread.

• Broken help_url anchor — 13_settings_rfid_reader.yaml pointed to #alternative-detection-system (singular) but the corresponding docs heading is ## Alternative Detection Systems, which generates the anchor #alternative-detection-systems. The ? button in the firmware-config UI would silently 404 on this anchor.

• No error handling in openrfid.py — _snapmaker_key() would crash with an unhelpful AttributeError: 'NoneType' object has no attribute 'group' if the Klipper RFID driver file was missing or had been updated to rename the HKDF key constant. It now prints a descriptive message to stderr and exits with code 1 in both failure cases.

Test plan

• With no prior filament-detect service installed: enable OpenRFID and confirm the PID file is created at /var/run/openrfid.pid
• Confirm S99openrfid stop cleans up /var/run/openrfid.pid
• Enable OpenRFID (force generic vendor): confirm only the confirm dialog message appears; no extra text in the action output
• Click the ? help icon on the Filament Detection setting: confirm it navigates to the correct docs anchor
• Remove fm175xx_reader.py temporarily and run openrfid.py: confirm a clear error message is printed instead of an AttributeError

🤖 Generated with Claude Code

[github-actions]

✅ Build Artifacts

Version: 1.1.1-paxx12-test-pr-321
Build: 87283c2 (merge of 91b696c into develop)
Duration: 5m 17s

Artifact	Size
extended-devel-build	240.69 MB
basic-devel-build	205.72 MB
extended-build	240.28 MB
basic-build	205.31 MB

View workflow run

[kbaker827]

Test plan results

Going through each item — static analysis for the items that don't need printer hardware, live Python execution for #5.

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✅ Test 1 & 2 — PIDFILE path and stop cleanup

All references to PIDFILE in S99openrfid now point to /var/run/openrfid.pid. No remaining references to filament-detect.pid:

line 3:  PIDFILE="/var/run/openrfid.pid"
line 24: if [ -f "$PIDFILE" ] && kill -0 "$(cat "$PIDFILE")" 2>/dev/null;  # already-running guard
line 36: start-stop-daemon -S -b -m -p "$PIDFILE" ...                       # start writes PID here
line 47: if [ -f "$PIDFILE" ];                                               # stop checks
line 48: start-stop-daemon -K -p "$PIDFILE" -s TERM                         # stop kills
line 49: rm -f "$PIDFILE"                                                    # stop cleans up

The stop() function correctly removes the file after sending SIGTERM. ✅

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✅ Test 3 — No stray echo in 15_settings_openrfid.yaml

grep for echo and Please read finds only the two confirm: keys (which are correct and intentional) — nothing inside any cmd: block:

line 8:  confirm: Please read the relevant documentation...   ← openrfid confirm
line 20: confirm: Please read the relevant documentation...   ← openrfid-generic confirm

No echo in any bash cmd. ✅

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✅ Test 4 — help_url anchor matches docs heading

	Value
help_url in YAML	…/rfid_support#alternative-detection-systems
Heading in docs/rfid_support.md (line 123)	## Alternative Detection Systems
Generated anchor	#alternative-detection-systems

Exact match. ✅

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✅ Test 5 — openrfid.py error handling

Ran all three paths of _snapmaker_key() locally:

5a — driver file missing:

exit code: 1
stderr:    Error: cannot read Klipper RFID driver: [Errno 2] No such file or directory: '/nonexistent/path.py'

PASS ✅ (was previously AttributeError or FileNotFoundError with no context)

5b — file present but HKDF key constant not found:

exit code: 1
stderr:    Error: Snapmaker HKDF key not found. The firmware driver may have changed.

PASS ✅ (was previously AttributeError: 'NoneType' object has no attribute 'group')

5c — key found, correct hex returned:

exit code: 0
stdout:    736e61706d616b65725f7365637265745f6b65795f68657265   ← correct hex encoding

PASS ✅

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All 5 test plan items verified. 🟢