add pgcron + scheduling primitives to Durable

[virajmehta]

Note

Medium Risk
Adds new database schema/migration and client methods that create/unschedule pg_cron jobs and inject reserved headers, which can affect queue lifecycle and production Postgres configuration/permissions. CI and tests now rely on a custom Postgres image with pg_cron, so failures are more likely to be environment-related than pure logic regressions.

Overview
Adds cron scheduling support via pg_cron: new Durable::{create_schedule,list_schedules,delete_schedule} APIs plus setup_pgcron() and exported schedule types (ScheduleOptions, ScheduleInfo, ScheduleFilter).

Introduces a durable.cron_schedules registry table (with metadata/task indexes) and updates durable.drop_queue() to also unschedule/remove any cron jobs tied to a queue; includes a new SQL migration and updates sql/schema.sql accordingly.

Updates CI to start Postgres via docker compose using a custom image configured for pg_cron, adds end-to-end cron tests (including verifying a cron job actually spawns tasks), and documents the new scheduling feature in README.md.

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[chatgpt-codex-connector]

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[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

Autofix Details

Bugbot Autofix prepared fixes for both issues found in the latest run.

• ✅ Fixed: README uses "PostgreSQL" instead of "Postgres"
  • Updated the README line to use "Postgres" in the pg_cron integration description to match project convention.
• ✅ Fixed: Dollar-quoting breaks when content ends with tag prefix
  • Adjusted pg_literal to fall back when input ends with $durable and added a unit test covering this delimiter-boundary edge case.

Or push these changes by commenting:

@cursor push 07c4b46d0a

Preview (07c4b46d0a)

diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -326,7 +326,7 @@
 
 **Key behaviors:**
 
-- **pg_cron integration** - Schedules are backed by PostgreSQL's pg_cron extension. At each tick, pg_cron inserts a task into the queue via `durable.spawn_task()`, and workers pick it up normally.
+- **pg_cron integration** - Schedules are backed by Postgres's pg_cron extension. At each tick, pg_cron inserts a task into the queue via `durable.spawn_task()`, and workers pick it up normally.
 - **Upsert semantics** - Calling `create_schedule` with an existing name updates the schedule in place.
 - **Origin tracking** - Scheduled tasks automatically receive `durable::scheduled_by` and `durable::cron` headers, so tasks can identify how they were spawned.
 - **Metadata filtering** - Attach arbitrary JSON metadata to schedules and filter with JSONB containment queries.

diff --git a/src/cron.rs b/src/cron.rs
--- a/src/cron.rs
+++ b/src/cron.rs
@@ -504,9 +504,10 @@
 // --- SQL escaping ---
 
 /// Dollar-quote a string using `$durable$` as the delimiter.
-/// Falls back to escaped single quotes if the content contains `$durable$`.
+/// Falls back to escaped single quotes if the content contains `$durable$`
+/// or ends with `$durable` (which would collide with the closing delimiter).
 fn pg_literal(s: &str) -> String {
-    if !s.contains("$durable$") {
+    if !s.contains("$durable$") && !s.ends_with("$durable") {
         format!("$durable${s}$durable$")
     } else {
         // Fallback: single-quote escaping (double up any single quotes)
@@ -725,6 +726,12 @@
         assert_eq!(pg_literal(content), "'has $durable$ and ''quotes'''");
     }
 
+    #[test]
+    fn test_pg_literal_fallback_when_content_ends_with_delimiter_prefix() {
+        let content = "test$durable";
+        assert_eq!(pg_literal(content), "'test$durable'");
+    }
+
     // --- Schedule name validation tests ---
 
     #[test]

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[shuyangli]

generally lgtm minus one thing