Fix schedule persistence: use read-modify-write instead of full rewrite

Message

save-config! was serializing the entire in-memory active-schedules list to minder.yaml. If active-schedules was empty or incomplete when this ran, all existing schedules in the file were clobbered.

Replace with add-schedule-to-config! that reads the current file, merges the single new/updated entry, and writes back — matching the pattern remove-schedule-from-config! already used.

Also: - One-time schedules no longer persist to config (the format can't represent the one-time flag, and they auto-remove after firing) - Extract shared YAML serialization into schedules->yaml-lines and write-schedules-config! helpers - Suppress config-watcher reload after our own writes to avoid redundant re-parsing

Changed

 src/minder/scheduler.sgl | 83 +++++++++++++++++++++++++++++++++++++++++++++--------------------------------------
 1 file changed, 45 insertions(+), 38 deletions(-)

Diff

src/minder/scheduler.sglmodified

@@ -29,6 +29,9 @@

;; Mutable alist of (name handle cron prompt one-time?)

(define active-schedules '())

+32

;; Flag to suppress config-watcher reload after our own writes.

+33

(define suppress-reload? #f)

+34

(define (get-active name)

(let ((pair (assoc name active-schedules)))

(and pair (cdr pair))))

@@ -133,9 +136,12 @@

136

(when (file-exists? "minder.yaml")

137

(let ((current-mtime (file-mtime "minder.yaml")))

138

(when (> current-mtime last-mtime)

−136

(log-info "minder.yaml changed, reloading schedules")

−137

(reload-schedules! server)

−138

(set! last-mtime current-mtime))))

+139

(set! last-mtime current-mtime)

+140

(if suppress-reload?

+141

(set! suppress-reload? #f)

+142

(begin

+143

(log-info "minder.yaml changed, reloading schedules")

+144

(reload-schedules! server))))))

145

(loop))))

146

147

;; Reload schedules from minder.yaml, only touching changed ones.

@@ -172,43 +178,43 @@

178

;; Config File Persistence

179

;; ============================================================

180

−175

;; Write the current schedule state to minder.yaml.

−176

(define (save-config!)

−177

(let ((lines '()))

−178

(when (pair? active-schedules)

−179

(set! lines (list "schedules:"))

−180

(for-each

−181

(lambda (entry)

−182

(let ((name (car entry))

−183

(cron (caddr entry))

−184

(desc (cadddr entry)))

−185

(set! lines (append lines

−186

(list (format " ~a:" name)

−187

(format " cron: \"~a\"" cron)

−188

(format " prompt: ~a" desc))))))

−189

active-schedules))

+181

;; Serialize schedule-config records to YAML lines.

+182

(define (schedules->yaml-lines schedules)

+183

(if (pair? schedules)

+184

(cons "schedules:"

+185

(apply append

+186

(map (lambda (sched)

+187

(list (format " ~a:" (schedule-config-name sched))

+188

(format " cron: \"~a\"" (schedule-config-cron sched))

+189

(format " prompt: ~a" (schedule-config-prompt sched))))

+190

schedules)))

+191

'()))

+192

+193

;; Write a list of schedule-config records to minder.yaml.

+194

(define (write-schedules-config! schedules)

+195

(guard (e (else

+196

(log-error (format "Failed to update config: ~a" e))))

+197

(set! suppress-reload? #t)

198

(write-file-string "minder.yaml"

−191

(string-append (string-join lines "\n") "\n"))))

+199

(string-append (string-join (schedules->yaml-lines schedules) "\n") "\n"))))

+200

+201

;; Add or update a single schedule in minder.yaml via read-modify-write.

+202

(define (add-schedule-to-config! name cron desc)

+203

(let* ((current (load-minder-config))

+204

(existing (filter

+205

(lambda (s) (not (equal? (schedule-config-name s) name)))

+206

(minder-config-schedules current)))

+207

(updated (append existing

+208

(list (schedule-config name: name cron: cron prompt: desc)))))

+209

(write-schedules-config! updated)))

210

211

;; Remove a single schedule from minder.yaml without touching others.

212

(define (remove-schedule-from-config! name)

−195

(guard (e (else

−196

(log-error (format "Failed to update config: ~a" e))))

−197

(let* ((current (load-minder-config))

−198

(remaining (filter

−199

(lambda (s) (not (equal? (schedule-config-name s) name)))

−200

(minder-config-schedules current)))

−201

(lines (if (pair? remaining)

−202

(cons "schedules:"

−203

(apply append

−204

(map (lambda (sched)

−205

(list (format " ~a:" (schedule-config-name sched))

−206

(format " cron: \"~a\"" (schedule-config-cron sched))

−207

(format " prompt: ~a" (schedule-config-prompt sched))))

−208

remaining)))

−209

'())))

−210

(write-file-string "minder.yaml"

−211

(string-append (string-join lines "\n") "\n")))))

+213

(let* ((current (load-minder-config))

+214

(remaining (filter

+215

(lambda (s) (not (equal? (schedule-config-name s) name)))

+216

(minder-config-schedules current))))

+217

(write-schedules-config! remaining)))

218

219

;; ============================================================

220

;; MCP Tools

@@ -258,8 +264,9 @@

264

(cancel-schedule! name))

265

;; Register the schedule

266

(register-schedule! server name cron desc one-time?: one-time?)

−261

;; Persist to config

−262

(save-config!)

+267

;; Persist to config (skip one-time schedules — they auto-remove)

+268

(unless one-time?

+269

(add-schedule-to-config! name cron desc))

270

(format "Schedule '~a' added~a: ~a" name

271

(if one-time? " (one-time)" "") cron))))

272