diff --git a/.agnostic-ai/AGNOSTIC_AI.md b/.agnostic-ai/AGNOSTIC_AI.md
index 1c985231..20695bcf 100644
--- a/.agnostic-ai/AGNOSTIC_AI.md
+++ b/.agnostic-ai/AGNOSTIC_AI.md
@@ -13,8 +13,8 @@ Preserve Bash 3.0 parsing and public APIs; follow sibling tests/code. Update doc
 Main selects checks by changed behavior/risk and reuses unchanged passes. Small fixes: affected tests, ShellCheck, `make lint`; strict mode for options, errors, hooks, or workers. Cross-cutting runtime changes/releases need:
 
 ```bash
-make test
-make test/strict
+BASHUNIT_PARALLEL_JOBS=4 make test
+BASHUNIT_PARALLEL_JOBS=4 make test/strict
 make sa
 make lint
 ```
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6260e4c3..0d778925 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,37 +9,41 @@
 
 ### Fixed
 
-- Snapshots record and update literal `-n`, `-e`, `-E` and combined echo flag values correctly (#1402)
-- Generated workflows run test directories containing whitespace as a single path without requiring a committed `.env` (#1425)
-- Annotations, tags, header counts and duplicate checks support functions declared without parentheses (#1422)
-- Echo data providers keep `#` and parentheses, and report malformed rows without dropping later rows. Quoted values keep carriage returns on Windows (#1419)
+#### Documentation
+
 - Homepage logo follows reduced-motion preferences and stops tracking the pointer after navigation
 - Primary buttons use dark text in both themes, including hover and active states
 - Quickstart commands match install.sh, npm project and npm global installs
-- A green file or filtered subset preserves rerun-cache entries for tests it did not execute (#1418)
-- SIGTERM and SIGHUP run teardown hooks, stop parallel workers, and remove the run's scratch files before exiting with status 1 (#1417)
-- Sequential stop-on-failure runs write requested reports and the rerun cache for the tests that ran (#1415)
-- Include, inline, and exclusion filters preserve `test_` inside names such as `latest_version` (#1414)
-- `.bashunitrc` suite options stay out of the environment, while global settings before and after suite sections still apply (#1410)
-- `install.sh` rejects prefixed or incomplete version numbers instead of treating them as directories (#1409)
-- `install.sh` resolves relative destinations from the caller's directory and reports the resolved installation path (#1408)
-- `bashunit::unmock` restores a shell function replaced by a spy, mock, or mock sequence (#1401)
-- Spies keep a multiline argument in one recorded call, including call comparisons and failure logs (#1399)
-- Parallel results and hook output stay separate for test paths that differ by slashes and underscores (#1416)
-- Coverage report paths are checked before tests run, and LCOV or HTML write failures make the run fail instead of reporting success (#1412)
-- `upgrade` keeps the installed binary when a download fails or returns an empty file (#1407)
-- `install.sh` keeps the installed binary when a download fails, is empty, or fails checksum verification (#1406)
-- `--debug` leaves an existing test file or directory as the test path instead of taking it as the trace file (#1405)
-- Call argument assertions fail when the spy was never called or the requested call index does not exist (#1400)
-- `assert_matches` and `assert_not_matches` accept patterns starting with `-` and fail when grep rejects a pattern (#1398)
+
+#### Assertions and doubles
+
+- Date assertions reject trailing text on macOS and parse colon-separated timezone offsets consistently across platforms (#1404)
+- `assert_string_not_starts_with` joins every haystack argument and uses the test name as its failure label, matching its siblings (#1403). `assert_matches` and `assert_not_matches` accept patterns starting with `-` and fail when grep rejects a pattern (#1398)
 - `assert_files_equals` and `assert_files_not_equals` fail and name the missing path when either file does not exist (#1397)
-- TAP reports keep test titles containing line breaks on a single result line (#1413)
+- Snapshots record and update literal `-n`, `-e`, `-E` and combined echo flag values correctly (#1402)
+- Spies keep multiline arguments in one recorded call, including comparisons and failure logs (#1399). Call argument assertions fail when the spy was never called or the requested call index does not exist (#1400)
+- `bashunit::unmock` restores shell functions replaced by spies, mocks or mock sequences (#1401)
+
+#### Setup and selection
+
+- `install.sh` and `upgrade` keep the installed binary when a download fails or is empty; installation also keeps it when checksum verification fails (#1406, #1407)
+- `install.sh` resolves relative destinations from the caller's directory, reports the resolved path (#1408), and rejects prefixed or incomplete version numbers instead of treating them as directories (#1409)
+- `init` quotes the bootstrap path and custom tests directory in `.env`, so paths containing spaces work on later runs (#1411). Generated workflows pass a tests directory containing whitespace as one path without requiring a committed `.env` (#1425)
+- `.bashunitrc` suite options stay out of the environment; global settings before and after suite sections still apply (#1410)
+- Include, inline and exclusion filters preserve `test_` inside names such as `latest_version` (#1414). `--debug` keeps an existing test file or directory as the test path instead of taking it as the trace file (#1405)
+
+#### Test discovery and execution
+
+- Annotations, tags, header counts and duplicate checks support functions declared without parentheses (#1422). Duplicate definitions with an opening brace on the next line are reported instead of replacing the first definition (#1421)
+- Echo data providers keep `#` and parentheses, and report malformed rows without dropping later rows. Quoted values keep carriage returns on Windows (#1419)
+- SIGTERM and SIGHUP run teardown hooks, stop parallel workers and remove scratch files before exiting with status 1 (#1417)
+- Parallel results and hook output stay separate for paths that differ by slashes and underscores (#1416). Relative hidden paths are counted and keep separate results from matching visible paths (#1393)
+
+#### Reports and reruns
 
-- `init` writes the bootstrap path and a custom tests directory to `.env` quoted, so a directory with a space runs afterwards instead of breaking every next run (#1411)
+- Sequential stop-on-failure runs write requested reports and the rerun cache for tests that ran (#1415). A green file or filtered subset preserves cache entries for tests it did not execute (#1418)
+- Coverage report paths are checked before tests run; LCOV or HTML write failures make the run fail (#1412). TAP reports keep test titles containing line breaks on one result line (#1413)
 - Failure source context stays inside a one-line test instead of listing the next function's assertions (#1420)
-- Parallel runs count tests under relative hidden paths and keep their results separate from matching visible paths (#1393)
-- Duplicate test functions are detected when the opening brace is on the next line instead of silently replacing the first definition (#1421)
-- `assert_string_not_starts_with` treats variadic haystack arguments as one newline-joined value and keeps failures labeled with the test's name (#1403)
 
 ### Changed
 
diff --git a/docs/assertions.md b/docs/assertions.md
index 915af3aa..69bfbb04 100644
--- a/docs/assertions.md
+++ b/docs/assertions.md
@@ -527,7 +527,7 @@ Inputs are automatically converted to epoch seconds. Supported formats:
 - ISO 8601 date: `2023-11-14`
 - ISO 8601 datetime: `2023-11-14T12:00:00`
 - ISO 8601 datetime with UTC Z: `2023-11-14T12:00:00Z`
-- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100`
+- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100` or `2023-11-14T12:00:00+01:00`
 - Space-separated datetime: `2023-11-14 12:00:00`
 
 You can mix formats in the same assertion (e.g., one epoch, one ISO).
diff --git a/src/assert/dates.sh b/src/assert/dates.sh
index 83a57bb7..1b188908 100644
--- a/src/assert/dates.sh
+++ b/src/assert/dates.sh
@@ -1,15 +1,28 @@
 #!/usr/bin/env bash
 
+function bashunit::date::_bsd_to_epoch() {
+  local input="$1" format
+  local date_pattern='[0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]'
+  local time_pattern='[0-9][0-9]:[0-9][0-9]:[0-9][0-9]'
+  # shellcheck disable=SC2254 # Date-shape glob patterns must expand unquoted.
+  case "$input" in
+  $date_pattern"T"${time_pattern}[+-][0-9][0-9][0-9][0-9]) format="%Y-%m-%dT%H:%M:%S%z" ;;
+  $date_pattern"T"$time_pattern) format="%Y-%m-%dT%H:%M:%S" ;;
+  $date_pattern" "$time_pattern) format="%Y-%m-%d %H:%M:%S" ;;
+  $date_pattern)
+    input="$input 00:00:00"
+    format="%Y-%m-%d %H:%M:%S"
+    ;;
+  *) return 1 ;;
+  esac
+  # BSD date accepts an unparsed suffix, so validate the complete shape first.
+  date -j -f "$format" "$input" +%s 2>/dev/null
+}
+
 function bashunit::date::to_epoch() {
   local input="$1"
 
-  # An empty string is never a date, and it has to be rejected here rather than
-  # left to the cascade below, because the two date(1) implementations disagree
-  # about it: GNU reads `date -d ""` as "now" and exits 0, while on BSD/macOS
-  # -d is not even a valid option. Falling through therefore resolved two empty
-  # inputs to the same epoch and compared them equal on Linux while correctly
-  # failing on macOS. It also matched the all-digits fast path below vacuously
-  # (an empty string contains no non-digit characters).
+  # GNU date treats an empty input as now; date assertions must reject it.
   if [ -z "$input" ]; then
     echo "$input"
     return 1
@@ -24,6 +37,10 @@ function bashunit::date::to_epoch() {
     ;;
   esac
 
+  case "$input" in
+  *[+-][0-9][0-9]:[0-9][0-9]) input="${input%:??}${input##*:}" ;;
+  esac
+
   # Handle Z (UTC) suffix explicitly: BusyBox needs TZ=UTC, BSD needs +0000
   case "$input" in
   *Z)
@@ -34,7 +51,7 @@ function bashunit::date::to_epoch() {
     epoch=$(TZ=UTC date -d "$utc_input" +%s 2>/dev/null) && { echo "$epoch"; return 0; }
     epoch=$(TZ=UTC date -d "$utc_norm" +%s 2>/dev/null) && { echo "$epoch"; return 0; }
     # BSD: use +0000 offset which %z understands
-    epoch=$(date -j -f "%Y-%m-%dT%H:%M:%S%z" "${utc_input}+0000" +%s 2>/dev/null) && { echo "$epoch"; return 0; }
+    epoch=$(bashunit::date::_bsd_to_epoch "${utc_input}+0000") && { echo "$epoch"; return 0; }
     echo "$input"
     return 1
     ;;
@@ -82,29 +99,13 @@ function bashunit::date::to_epoch() {
       return 0
     }
   fi
-  # Try BSD date (-j -f flag) with ISO 8601 datetime + timezone offset
-  epoch=$(date -j -f "%Y-%m-%dT%H:%M:%S%z" "$input" +%s 2>/dev/null) && {
-    echo "$epoch"
-    return 0
-  }
-  # Try BSD date with ISO 8601 datetime format
-  epoch=$(date -j -f "%Y-%m-%dT%H:%M:%S" "$input" +%s 2>/dev/null) && {
-    echo "$epoch"
-    return 0
-  }
-  # Try BSD date with space-separated datetime format
-  epoch=$(date -j -f "%Y-%m-%d %H:%M:%S" "$input" +%s 2>/dev/null) && {
-    echo "$epoch"
-    return 0
-  }
-  # Try BSD date with date-only format (append midnight for deterministic results)
-  epoch=$(date -j -f "%Y-%m-%d %H:%M:%S" "$input 00:00:00" +%s 2>/dev/null) && {
+  epoch=$(bashunit::date::_bsd_to_epoch "$input") && {
     echo "$epoch"
     return 0
   }
 
   # Unsupported format
-  echo "$input"
+  echo "$1"
   return 1
 }
 
diff --git a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
index 9c0a2f21..8f872cc2 100644
--- a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
+++ b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_all_assert_docs.snapshot
@@ -216,7 +216,7 @@ Inputs are automatically converted to epoch seconds. Supported formats:
 - ISO 8601 date: `2023-11-14`
 - ISO 8601 datetime: `2023-11-14T12:00:00`
 - ISO 8601 datetime with UTC Z: `2023-11-14T12:00:00Z`
-- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100`
+- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100` or `2023-11-14T12:00:00+01:00`
 - Space-separated datetime: `2023-11-14 12:00:00`
 
 You can mix formats in the same assertion (e.g., one epoch, one ISO).
diff --git a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_filtered_assert_docs.snapshot b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_filtered_assert_docs.snapshot
index 1540e821..e564560a 100644
--- a/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_filtered_assert_docs.snapshot
+++ b/tests/acceptance/snapshots/bashunit_test_sh.test_bashunit_should_display_filtered_assert_docs.snapshot
@@ -22,7 +22,7 @@ Inputs are automatically converted to epoch seconds. Supported formats:
 - ISO 8601 date: `2023-11-14`
 - ISO 8601 datetime: `2023-11-14T12:00:00`
 - ISO 8601 datetime with UTC Z: `2023-11-14T12:00:00Z`
-- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100`
+- ISO 8601 datetime with timezone offset: `2023-11-14T12:00:00+0100` or `2023-11-14T12:00:00+01:00`
 - Space-separated datetime: `2023-11-14 12:00:00`
 
 You can mix formats in the same assertion (e.g., one epoch, one ISO).
diff --git a/tests/unit/assert/dates_test.sh b/tests/unit/assert/dates_test.sh
index fb498ab8..b7d97021 100644
--- a/tests/unit/assert/dates_test.sh
+++ b/tests/unit/assert/dates_test.sh
@@ -14,6 +14,44 @@ function test_unsuccessful_assert_date_equals() {
     "$(assert_date_equals "1700000000" "1600000000")"
 }
 
+function test_unsuccessful_assert_date_equals_with_trailing_text() {
+  assert_same\
+    "$(bashunit::console_results::print_failed_test\
+      "Unsuccessful assert date equals with trailing text"\
+      "2024-01-01T10:00:00 nonsense" "to be" "a valid date")"\
+    "$(assert_date_equals "2024-01-01T10:00:00 nonsense" "2024-01-01T10:00:00")"
+}
+
+function test_successful_assert_date_equals_with_colon_offset() {
+  assert_empty "$(assert_date_equals "2024-01-01T10:00:00+0200" "2024-01-01T10:00:00+02:00")"
+  assert_empty "$(assert_date_equals "1704096000" "2024-01-01T10:00:00+02:00")"
+}
+
+function test_successful_assert_date_equals_with_negative_colon_offset() {
+  assert_empty "$(assert_date_equals "2024-01-01T10:00:00-0430" "2024-01-01T10:00:00-04:30")"
+  assert_empty "$(assert_date_equals "1704119400" "2024-01-01T10:00:00-04:30")"
+}
+
+function test_date_parser_rejects_trailing_text_in_each_supported_shape() {
+  local input actual code
+  for input in \
+    '2024-01-01 nonsense' \
+    '2024-01-01 10:00:00 nonsense' \
+    '2024-01-01T10:00:00+0200 nonsense' \
+    '2024-01-01T10:00:00+02:00 nonsense' \
+    '2024-01-01T10:00:00 nonsenseZ'; do
+    code=0
+    actual=$(bashunit::date::to_epoch "$input") || code=$?
+    assert_same 1 "$code"
+    assert_same "$input" "$actual"
+  done
+}
+
+function test_successful_assert_date_equals_preserves_explicit_timezone_epochs() {
+  assert_empty "$(assert_date_equals "1704096000" "2024-01-01T10:00:00+0200")"
+  assert_empty "$(assert_date_equals "1704103200" "2024-01-01T10:00:00Z")"
+}
+
 function test_successful_assert_date_before() {
   assert_empty "$(assert_date_before "1700000000" "1600000000")"
 }