feat(timezone): use Google account timezone for day-boundary calculations

Replace machine-local chrono::Local and UTC epoch math with the
authenticated user's Google account timezone (Calendar Settings API).

- Add chrono-tz dependency for IANA timezone parsing
- New src/timezone.rs: resolve timezone with priority:
  --timezone flag > 24h cache > Calendar API > local fallback
- calendar.rs: add --timezone/--tz flag to +agenda
- workflows.rs: fix +standup-report, +weekly-digest, +meeting-prep
- auth_commands.rs: invalidate timezone cache on logout
- Update README.md and AGENTS.md with timezone docs

Supersedes #369 and #462.

Author: jpoehnelt-bot

.changeset/account-timezone.md

@@ -0,0 +1,5 @@
+---
+"@googleworkspace/cli": minor
+---
+
+Use Google account timezone instead of machine-local time for day-boundary calculations in calendar and workflow helpers. Adds `--timezone` flag to `+agenda` for explicit override. Timezone is fetched from Calendar Settings API and cached for 24 hours.

AGENTS.md

@@ -57,6 +57,7 @@ The CLI uses a **two-phase argument parsing** strategy:
 | `src/schema.rs`           | `gws schema` command — introspect API method schemas                                      |
 | `src/error.rs`            | Structured JSON error output                                                              |
 | `src/logging.rs`          | Opt-in structured logging (stderr + file) via `tracing`                                   |
+| `src/timezone.rs`         | Account timezone resolution: `--timezone` flag, Calendar Settings API, 24h cache           |
 
 ## Demo Videos
 

Cargo.lock

@@ -54,6 +54,8 @@ derive_builder = "0.20.2"
 ratatui = "0.30.0"
 crossterm = "0.29.0"
 chrono = "0.4.44"
+chrono-tz = "0.10"
+iana-time-zone = "0.1"
 async-trait = "0.1.89"
 serde_yaml = "0.9.34"
 percent-encoding = "2.3.2"

Cargo.toml

@@ -296,6 +296,8 @@ gws sheets spreadsheets values append \
 
 Some services ship hand-crafted helper commands alongside the auto-generated Discovery surface. Helper commands are prefixed with `+` so they are visually distinct and never collide with Discovery-generated method names.
 
+Time-aware helpers (`+agenda`, `+standup-report`, `+weekly-digest`, `+meeting-prep`) automatically use your **Google account timezone** (fetched from Calendar Settings API and cached for 24 hours). Override with `--timezone`/`--tz` on `+agenda`, or set the `--timezone` flag for explicit control.
+
 Run `gws <service> --help` to see both Discovery methods and helper commands together.
 
 ```bash
@@ -320,7 +322,7 @@ gws drive --help      # shows +upload …
 | `chat` | `+send` | Send a message to a space |
 | `drive` | `+upload` | Upload a file with automatic metadata |
 | `calendar` | `+insert` | Create a new event |
-| `calendar` | `+agenda` | Show upcoming events across all calendars |
+| `calendar` | `+agenda` | Show upcoming events (uses Google account timezone; override with `--timezone`) |
 | `script` | `+push` | Replace all files in an Apps Script project with local files |
 | `workflow` | `+standup-report` | Today's meetings + open tasks as a standup summary |
 | `workflow` | `+meeting-prep` | Prepare for your next meeting: agenda, attendees, and linked docs |
@@ -353,6 +355,9 @@ gws drive +upload ./report.pdf --name "Q1 Report"
 
 # Morning standup summary
 gws workflow +standup-report
+
+# Show today's agenda in a specific timezone
+gws calendar +agenda --today --timezone America/New_York
 ```
 
 ### Model Armor (Response Sanitization)

README.md

@@ -31,6 +31,7 @@ gws calendar +agenda
 | `--week` | — | — | Show this week's events |
 | `--days` | — | — | Number of days ahead to show |
 | `--calendar` | — | — | Filter to specific calendar name or ID |
+| `--timezone` | — | — | IANA timezone override (e.g. America/Denver). Defaults to Google account timezone. |
 
 ## Examples
 
@@ -39,12 +40,14 @@ gws calendar +agenda
 gws calendar +agenda --today
 gws calendar +agenda --week --format table
 gws calendar +agenda --days 3 --calendar 'Work'
+gws calendar +agenda --today --timezone America/New_York
 ```
 
 ## Tips
 
 - Read-only — never modifies events.
 - Queries all calendars by default; use --calendar to filter.
+- Uses your Google account timezone by default; override with --timezone.
 
 ## See Also
 

skills/gws-calendar-agenda/SKILL.md

@@ -1191,6 +1191,9 @@ fn handle_logout() -> Result<(), GwsError> {
         }
     }
 
+    // Invalidate cached account timezone (may belong to old account)
+    crate::timezone::invalidate_cache();
+
     let output = if removed.is_empty() {
         json!({
             "status": "success",

src/auth_commands.rs

@@ -122,17 +122,26 @@ TIPS:
                         .help("Filter to specific calendar name or ID")
                         .value_name("NAME"),
                 )
+                .arg(
+                    Arg::new("timezone")
+                        .long("timezone")
+                        .alias("tz")
+                        .help("IANA timezone override (e.g. America/Denver). Defaults to Google account timezone.")
+                        .value_name("TZ"),
+                )
                 .after_help(
                     "\
 EXAMPLES:
   gws calendar +agenda
   gws calendar +agenda --today
   gws calendar +agenda --week --format table
   gws calendar +agenda --days 3 --calendar 'Work'
+  gws calendar +agenda --today --timezone America/New_York
 
 TIPS:
   Read-only — never modifies events.
-  Queries all calendars by default; use --calendar to filter.",
+  Queries all calendars by default; use --calendar to filter.
+  Uses your Google account timezone by default; override with --timezone.",
                 ),
         );
         cmd
@@ -201,21 +210,14 @@ async fn handle_agenda(matches: &ArgMatches) -> Result<(), GwsError> {
         .map(|s| crate::formatter::OutputFormat::from_str(s))
         .unwrap_or(crate::formatter::OutputFormat::Table);
 
-    // Determine time range using the local timezone so that --today and
-    // --tomorrow align with the user's wall-clock day, not UTC.
-    use chrono::{Local, NaiveTime, TimeZone};
-
-    let local_now = Local::now();
-    let today_start = local_now
-        .date_naive()
-        .and_time(NaiveTime::from_hms_opt(0, 0, 0).unwrap());
-    // Use .earliest() to handle DST transitions where midnight may be
-    // ambiguous or non-existent. Falls back to current time if resolution
-    // fails entirely (should not happen for midnight in practice).
-    let today_start_local = Local
-        .from_local_datetime(&today_start)
-        .earliest()
-        .unwrap_or(local_now);
+    let client = crate::client::build_client()?;
+    let tz_override = matches.get_one::<String>("timezone").map(|s| s.as_str());
+    let tz = crate::timezone::resolve_account_timezone(&client, &token, tz_override).await?;
+
+    // Determine time range using the account timezone so that --today and
+    // --tomorrow align with the user's Google account day, not the machine.
+    let now_in_tz = chrono::Utc::now().with_timezone(&tz);
+    let today_start_tz = crate::timezone::start_of_today(tz)?;
 
     let days: i64 = if matches.get_flag("tomorrow") {
         1
@@ -229,24 +231,24 @@ async fn handle_agenda(matches: &ArgMatches) -> Result<(), GwsError> {
     };
 
     let (time_min_dt, time_max_dt) = if matches.get_flag("today") {
-        // Today: local midnight to local midnight+1
-        let end = today_start_local + chrono::Duration::days(1);
-        (today_start_local, end)
+        // Today: account tz midnight to midnight+1
+        let end = today_start_tz + chrono::Duration::days(1);
+        (today_start_tz, end)
     } else if matches.get_flag("tomorrow") {
-        // Tomorrow: local midnight+1 to local midnight+2
-        let start = today_start_local + chrono::Duration::days(1);
-        let end = today_start_local + chrono::Duration::days(2);
+        // Tomorrow: account tz midnight+1 to midnight+2
+        let start = today_start_tz + chrono::Duration::days(1);
+        let end = today_start_tz + chrono::Duration::days(2);
         (start, end)
     } else {
         // From now, N days ahead
-        let end = local_now + chrono::Duration::days(days);
-        (local_now, end)
+        let end = now_in_tz + chrono::Duration::days(days);
+        (now_in_tz, end)
     };
 
     let time_min = time_min_dt.to_rfc3339();
     let time_max = time_max_dt.to_rfc3339();
 
-    let client = crate::client::build_client()?;
+    // client already built above for timezone resolution
     let calendar_filter = matches.get_one::<String>("calendar");
 
     // 1. List all calendars
@@ -547,35 +549,35 @@ mod tests {
         assert!(body.contains("c@d.com"));
     }
 
-    /// Verify that agenda day boundaries use local timezone offsets, not UTC.
+    /// Verify that agenda day boundaries use a specific timezone, not UTC.
     #[test]
-    fn agenda_day_boundaries_use_local_timezone() {
-        use chrono::{Local, NaiveTime, TimeZone};
+    fn agenda_day_boundaries_use_account_timezone() {
+        use chrono::{NaiveTime, TimeZone, Utc};
 
-        let local_now = Local::now();
-        let today_start = local_now
+        // Simulate using a known account timezone (America/Denver = UTC-7 / UTC-6 DST)
+        let tz = chrono_tz::America::Denver;
+        let now_in_tz = Utc::now().with_timezone(&tz);
+        let today_start = now_in_tz
             .date_naive()
             .and_time(NaiveTime::from_hms_opt(0, 0, 0).unwrap());
-        let today_start_local = Local
+        let today_start_tz = tz
             .from_local_datetime(&today_start)
             .earliest()
-            .unwrap_or(local_now.into());
+            .expect("midnight should resolve");
 
-        let today_rfc = today_start_local.to_rfc3339();
-        let tomorrow_start = today_start_local + chrono::Duration::days(1);
+        let today_rfc = today_start_tz.to_rfc3339();
+        let tomorrow_start = today_start_tz + chrono::Duration::days(1);
         let tomorrow_rfc = tomorrow_start.to_rfc3339();
 
-        // The local offset should appear in the RFC3339 string (e.g. -07:00, +05:30).
-        // If the code were using UTC, the string would end with +00:00 (unless
-        // the machine is actually in UTC, in which case this test is a no-op).
-        let local_offset = local_now.format("%:z").to_string();
+        // The Denver offset should appear in the RFC3339 string (-07:00 or -06:00 for DST).
+        // Crucially, it should NOT be +00:00 (UTC).
         assert!(
-            today_rfc.contains(&local_offset),
-            "today boundary should carry local offset {local_offset}, got {today_rfc}"
+            today_rfc.contains("-07:00") || today_rfc.contains("-06:00"),
+            "today boundary should carry Denver offset, got {today_rfc}"
         );
         assert!(
-            tomorrow_rfc.contains(&local_offset),
-            "tomorrow boundary should carry local offset {local_offset}, got {tomorrow_rfc}"
+            tomorrow_rfc.contains("-07:00") || tomorrow_rfc.contains("-06:00"),
+            "tomorrow boundary should carry Denver offset, got {tomorrow_rfc}"
         );
     }
 }