content-calendar-recurrence

Calendar recurrence: RFC5545 RRULE expansion with timezone/DST handling

Tier	content
Role	unclassified (baselined)
Path	`crates/content/calendar-recurrence`
Edition	2021
Targets	content_calendar_recurrence, integration
Public items	11 across 2 modules
Tests	28

What it is for

# content-calendar-recurrence

Calendar recurrence library crate: RFC5545 RRULE expansion with proper timezone/DST handling.

Architecture

This crate handles recurring events WITHOUT materializing instances:

Series: A template encounter + RRULE + timezone
Exceptions: Skip or override specific instances
Expansion: Compute instances on-demand via expand_occurrences()

Key Design Decisions

1. Timezone + Local Timestamp: Store dtstart_local (TIMESTAMP without TZ) plus an IANA timezone name (e.g., America/Chicago). This correctly handles DST: "Every Tuesday at 7pm" stays at 7pm local time even when clocks change.

2. No Materialized Instances: We don't pre-generate occurrence rows. Instead, expand_occurrences() computes them on-demand for a given date range.

3. Exceptions Table: Skip or override specific instances without breaking the series pattern.

4. Real FKs: Series references an encounter as template. No polymorphic linking.

Example

use content_calendar_recurrence::{CalendarSeries, Occurrence, expand_occurrences};
use chrono::{NaiveDateTime, Utc};

// Create a weekly series
let series = CalendarSeries::new(
encounter_template_id,
"FREQ=WEEKLY;BYDAY=TU,TH",
"America/Chicago",
NaiveDateTime::parse_from_str("2026-01-20 19:00:00", "%Y-%m-%d %H:%M:%S").unwrap(),
);

// Expand for January-March 2026
let from = Utc.with_ymd_and_hms(2026, 1, 1, 0, 0, 0).unwrap();
let to = Utc.with_ymd_and_hms(2026, 4, 1, 0, 0, 0).unwrap();
let occurrences = expand_occurrences(&series, &, from, to)?;

Capabilities

`Occurrence`

RRULE expansion with proper timezone/DST handling.

Item
`pub struct Occurrence`
`fn expand_occurrences(series : & CalendarSeries, exceptions : & SeriesException, from : DateTime <Utc>, to : DateTime <Utc>,) -> Result <Vec <Occurrence>, RecurrenceError>`

`postgres (other)`

PostgreSQL storage for calendar series and exceptions.

Item
`async fn create_series(pool : & PgPool, series : & CalendarSeries) -> Result <(), RecurrenceError>`
`async fn get_series(pool : & PgPool, id : SeriesId) -> Result <CalendarSeries, RecurrenceError>`
`async fn get_series_by_encounter(pool : & PgPool, encounter_id : Uuid,) -> Result <Option <CalendarSeries>, RecurrenceError>`
`async fn update_series(pool : & PgPool, series : & CalendarSeries) -> Result <(), RecurrenceError>`
`async fn delete_series(pool : & PgPool, id : SeriesId) -> Result <(), RecurrenceError>`
`async fn create_exception(pool : & PgPool, exception : & SeriesException,) -> Result <(), RecurrenceError>`
`async fn get_exceptions(pool : & PgPool, series_id : SeriesId,) -> Result <Vec <SeriesException>, RecurrenceError>`
`async fn delete_exception(pool : & PgPool, series_id : SeriesId, original_start_local : NaiveDateTime,) -> Result <(), RecurrenceError>`
`async fn list_series(pool : & PgPool) -> Result <Vec <CalendarSeries>, RecurrenceError>`

How to use it

No examples/ target and no doctest in this crate's rustdoc. The tests listed under Verification are the closest executable usage.

Module structure

content_calendar_recurrence

expand
postgres

flowchart TD
  n_content_calendar_recurrence["content_calendar_recurrence"]
  n_content_calendar_recurrence --> n_expand["expand"]
  n_content_calendar_recurrence --> n_postgres["postgres"]

Public surface

`expand`

Item	What it is
`pub struct Occurrence`	A single occurrence of a recurring event.
`fn expand_occurrences(series : & CalendarSeries, exceptions : & SeriesException, from : DateTime <Utc>, to : DateTime <Utc>,) -> Result <Vec <Occurrence>, RecurrenceError>`	Expand a recurrence rule into concrete occurrences within a date range

`postgres`

Item	What it is
`async fn create_series(pool : & PgPool, series : & CalendarSeries) -> Result <(), RecurrenceError>`	Create a new calendar series.
`async fn get_series(pool : & PgPool, id : SeriesId) -> Result <CalendarSeries, RecurrenceError>`	Get a calendar series by ID.
`async fn get_series_by_encounter(pool : & PgPool, encounter_id : Uuid,) -> Result <Option <CalendarSeries>, RecurrenceError>`	Get a calendar series by encounter template ID.
`async fn update_series(pool : & PgPool, series : & CalendarSeries) -> Result <(), RecurrenceError>`	Update a calendar series.
`async fn delete_series(pool : & PgPool, id : SeriesId) -> Result <(), RecurrenceError>`	Delete a calendar series.
`async fn create_exception(pool : & PgPool, exception : & SeriesException,) -> Result <(), RecurrenceError>`	Create a series exception.
`async fn get_exceptions(pool : & PgPool, series_id : SeriesId,) -> Result <Vec <SeriesException>, RecurrenceError>`	Get exceptions for a series.
`async fn delete_exception(pool : & PgPool, series_id : SeriesId, original_start_local : NaiveDateTime,) -> Result <(), RecurrenceError>`	Delete a series exception.
`async fn list_series(pool : & PgPool) -> Result <Vec <CalendarSeries>, RecurrenceError>`	List all series (for admin/debugging).

Re-exports. Exported here, defined elsewhere.

Export	Defined in
`PartyId`	`identity_parties::PartyId`
`RecurrenceError`	`error::RecurrenceError`
`{CalendarSeries,ExceptionAction,SeriesException,SeriesId}`	`models::{CalendarSeries,ExceptionAction,SeriesException,SeriesId}`
`{create_exception,create_series,delete_exception,delete_series,get_exceptions,get_series,get_series_by_encounter,list_series,update_series,}`	`postgres::{create_exception,create_series,delete_exception,delete_series,get_exceptions,get_series,get_series_by_encounter,list_series,update_series,}`
`{expand_occurrences,Occurrence}`	`expand::{expand_occurrences,Occurrence}`

Boundary

Reaches into foundation, identity.

Shares tier content with 5 other crates: content-assets, content-calendar, content-cms, content-directory-listing, content-notes.

_What this crate deliberately does NOT own is a judgment. No committed registry records one for it, so none is stated here._

Where it sits

Tier (ontology)	`content`
Architectural role (taxonomy)	`unclassified (baselined)`
Location	`crates/content/calendar-recurrence`
Vocabulary in force (lexicon)	`current`

Tier flow. Which tiers this crate's own edges cross.

flowchart LR
  n_content["content"] --> n_foundation["foundation"]
  n_content["content"] --> n_identity["identity"]

Dependencies

Runtime, in this workspace.

Crate	Tier	Optional	Only on
`foundation-basemodels`	foundation	no	always
`identity-parties`	identity	no	always

Runtime, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`async-trait`	`^0.1`	—	no	always
`chrono`	`^0.4`	`serde`	no	always
`chrono-tz`	`^0.10`	—	no	always
`rrule`	`^0.13`	—	no	always
`serde`	`^1`	`derive`	no	always
`serde_json`	`^1`	—	no	always
`sqlx`	`^0.8`	`runtime-tokio`, `postgres`, `chrono`, `uuid`, `json`	yes	always
`thiserror`	`^2`	—	no	always
`uuid`	`^1`	`v4`, `serde`	no	always

Development, from outside the workspace.

Crate	Requirement	Features	Optional	Only on
`dotenvy`	`^0.15`	—	no	always
`tokio`	`^1`	`full`	no	always
`tokio-test`	`^0.4`	—	no	always

Build. None.

Depended on by. 2 workspace crates.

Signal flow — what reaches this crate, and what it reaches.

flowchart LR
  n_application_calendar_recurrence["application-calendar-recurrence"] -->|uses| SELF
  n_foundation_test_support["foundation-test-support"] -->|uses| SELF
  SELF["content-calendar-recurrence"]
  SELF -->|runtime| n_foundation_basemodels["foundation-basemodels"]
  SELF -->|runtime| n_identity_parties["identity-parties"]
  classDef self fill:#1f883d,stroke:#1f883d,color:#fff;
  class SELF self;

Feature flags

Feature	Enables	On by default
`default`	—	yes
`postgres`	`dep:sqlx`	no

flowchart LR
  n_default["default"]
  n_postgres["postgres"] --> n_dep_sqlx["dep:sqlx"]

Targets

Kind	Name	Source
lib	`content_calendar_recurrence`	`src/lib.rs`
test	`integration`	`tests/integration.rs`

Error model

No public error type was detected: no public item declares a type named *Error, and no public signature returns one.

Operational characteristics

Property	Evidence
async public surface	yes
async runtime	none detected
database access	yes
network I/O	none detected
unsafe code	none detected
environment variables	none detected

No unsafe block, unsafe fn, unsafe impl or unsafe trait was found by the parser anywhere in this crate's source.

Configuration

No environment variable is read with a literal name anywhere in this crate. A variable whose key is computed at run time cannot be listed here, and is not claimed to be absent.

2 workspace crates depend on this one: application-calendar-recurrence, foundation-test-support.

Verification

Kind	Count
Unit tests	10
Integration tests	18
Examples	0
Doctests	0

Evidence by module. How often each public module is named by something executable.

Module	Tests	Examples	Consumers
`expand`	2	0	0
`postgres`	9	0	0

What the tests establish, by name:

test_cascade_delete_exceptions — tests/integration.rs
test_create_override_exception — tests/integration.rs
test_create_series — tests/integration.rs
test_create_skip_exception — tests/integration.rs
test_delete_exception — tests/integration.rs
test_delete_series — tests/integration.rs
test_duplicate_exception_fails — tests/integration.rs
test_expand_across_dst_fall_back — tests/integration.rs
test_expand_across_dst_spring_forward — tests/integration.rs
test_expand_weekly_occurrences — tests/integration.rs
test_expand_with_override_exception — tests/integration.rs
test_expand_with_skip_exception — tests/integration.rs
test_get_series_by_encounter — tests/integration.rs
test_get_series_by_encounter_not_found — tests/integration.rs
test_get_series_not_found — tests/integration.rs
test_invalid_timezone_error — tests/integration.rs
test_list_series — tests/integration.rs
test_update_series — tests/integration.rs
test_dst_spring_forward — src/expand.rs
test_expand_weekly_series — src/expand.rs
test_expand_with_override_exception — src/expand.rs
test_expand_with_skip_exception — src/expand.rs
test_invalid_timezone — src/expand.rs
test_exports — src/lib.rs
test_exception_action_parsing — src/models.rs
test_exception_skip — src/models.rs
test_series_builder — src/models.rs
test_exception_action_roundtrip — src/postgres.rs

Documentation coverage

Measure	Documented	Total
Public items with rustdoc	11	11
Public modules with a `//!` block	2	2

pie showData
    title Public items with rustdoc
    "Documented" : 11
    "No rustdoc detected" : 0

Metrics

Metric	Value
Rust source files	5
Source lines	915
Code lines	632
Public API items	11
Public modules	2
Tests	28
Examples	0
Cargo features	2
Direct runtime dependencies	11
Workspace reverse dependencies	2

pie showData
    title Public API by kind
    "function" : 10
    "struct" : 1

pie showData
    title Rust source composition
    "Code" : 632
    "Blank or comment" : 283

Generation

Rendered by tools-corpus corpus readme from repository evidence alone, renderer schema 2, lexicon current. No model, network service or database was consulted. Regenerate with tools-corpus corpus readme --write; verify with --check.