[web_server] Simplify datetime formatting with buf_append_printf

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

.claude/skills/pr-workflow/SKILL.md

@@ -0,0 +1,96 @@
+---
+name: pr-workflow
+description: Create pull requests for esphome. Use when creating PRs, submitting changes, or preparing contributions.
+allowed-tools: Read, Bash, Glob, Grep
+---
+
+# ESPHome PR Workflow
+
+When creating a pull request for esphome, follow these steps:
+
+## 1. Create Branch from Upstream
+
+Always base your branch on **upstream** (not origin/fork) to ensure you have the latest code:
+
+```bash
+git fetch upstream
+git checkout -b <branch-name> upstream/dev
+```
+
+## 2. Read the PR Template
+
+Before creating a PR, read `.github/PULL_REQUEST_TEMPLATE.md` to understand required fields.
+
+## 3. Create the PR
+
+Use `gh pr create` with the **full template** filled in. Never skip or abbreviate sections.
+
+Required fields:
+- **What does this implement/fix?**: Brief description of changes
+- **Types of changes**: Check ONE appropriate box (Bugfix, New feature, Breaking change, etc.)
+- **Related issue**: Use `fixes <link>` syntax if applicable
+- **Pull request in esphome-docs**: Link if docs are needed
+- **Test Environment**: Check platforms you tested on
+- **Example config.yaml**: Include working example YAML
+- **Checklist**: Verify code is tested and tests added
+
+## 4. Example PR Body
+
+```markdown
+# What does this implement/fix?
+
+<describe your changes here>
+
+## Types of changes
+
+- [ ] Bugfix (non-breaking change which fixes an issue)
+- [x] New feature (non-breaking change which adds functionality)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
+- [ ] Developer breaking change (an API change that could break external components)
+- [ ] Code quality improvements to existing code or addition of tests
+- [ ] Other
+
+**Related issue or feature (if applicable):**
+
+- fixes https://github.com/esphome/esphome/issues/XXX
+
+**Pull request in [esphome-docs](https://github.com/esphome/esphome-docs) with documentation (if applicable):**
+
+- esphome/esphome-docs#XXX
+
+## Test Environment
+
+- [x] ESP32
+- [x] ESP32 IDF
+- [ ] ESP8266
+- [ ] RP2040
+- [ ] BK72xx
+- [ ] RTL87xx
+- [ ] LN882x
+- [ ] nRF52840
+
+## Example entry for `config.yaml`:
+
+```yaml
+# Example config.yaml
+component_name:
+  id: my_component
+  option: value
+```
+
+## Checklist:
+  - [x] The code change is tested and works locally.
+  - [x] Tests have been added to verify that the new code works (under `tests/` folder).
+
+If user exposed functionality or configuration variables are added/changed:
+  - [ ] Documentation added/updated in [esphome-docs](https://github.com/esphome/esphome-docs).
+```
+
+## 5. Push and Create PR
+
+```bash
+git push -u origin <branch-name>
+gh pr create --repo esphome/esphome --base dev --title "[component] Brief description"
+```
+
+Title should be prefixed with the component name in brackets, e.g. `[safe_mode] Add feature`.

.github/actions/restore-python/action.yml

@@ -22,7 +22,7 @@ runs:
         python-version: ${{ inputs.python-version }}
     - name: Restore Python virtual environment
       id: cache-venv
-      uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+      uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
       with:
         path: venv
         # yamllint disable-line rule:line-length

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
       - name: Restore Python virtual environment
         id: cache-venv
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: venv
           # yamllint disable-line rule:line-length
@@ -157,7 +157,7 @@ jobs:
           token: ${{ secrets.CODECOV_TOKEN }}
       - name: Save Python virtual environment cache
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache/save@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/save@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: venv
           key: ${{ runner.os }}-${{ steps.restore-python.outputs.python-version }}-venv-${{ needs.common.outputs.cache-key }}
@@ -193,7 +193,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
       - name: Restore components graph cache
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: .temp/components_graph.json
           key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}
@@ -223,7 +223,7 @@ jobs:
           echo "component-test-batches=$(echo "$output" | jq -c '.component_test_batches')" >> $GITHUB_OUTPUT
       - name: Save components graph cache
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache/save@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/save@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: .temp/components_graph.json
           key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}
@@ -245,7 +245,7 @@ jobs:
           python-version: "3.13"
       - name: Restore Python virtual environment
         id: cache-venv
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: venv
           key: ${{ runner.os }}-${{ steps.python.outputs.python-version }}-venv-${{ needs.common.outputs.cache-key }}
@@ -334,14 +334,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
@@ -413,14 +413,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
@@ -502,14 +502,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
@@ -735,7 +735,7 @@ jobs:
       - name: Restore cached memory analysis
         id: cache-memory-analysis
         if: steps.check-script.outputs.skip != 'true'
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: memory-analysis-target.json
           key: ${{ steps.cache-key.outputs.cache-key }}
@@ -759,7 +759,7 @@ jobs:
 
       - name: Cache platformio
         if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-memory-${{ fromJSON(needs.determine-jobs.outputs.memory_impact).platform }}-${{ hashFiles('platformio.ini') }}
@@ -800,7 +800,7 @@ jobs:
 
       - name: Save memory analysis to cache
         if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true' && steps.build.outcome == 'success'
-        uses: actions/cache/save@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/save@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: memory-analysis-target.json
           key: ${{ steps.cache-key.outputs.cache-key }}
@@ -847,7 +847,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
       - name: Cache platformio
-        uses: actions/cache/restore@9255dc7a253b0ccc959486e2bca901246202afeb # v5.0.1
+        uses: actions/cache/restore@8b402f58fbc84540c8b491a91e594a4576fec3d7 # v5.0.2
         with:
           path: ~/.platformio
           key: platformio-memory-${{ fromJSON(needs.determine-jobs.outputs.memory_impact).platform }}-${{ hashFiles('platformio.ini') }}

esphome/components/mipi_dsi/models/guition.py

@@ -101,4 +101,225 @@ DriverChip(
         (0xFF, 0x77, 0x01, 0x00, 0x00, 0x00),
     ]
 )
+
+# jc8012P4A1 Driver Configuration (jd9365)
+# Using parameters from esp_lcd_jd9365.h and the working full init sequence
+# ----------------------------------------------------------------------------------------------------------------------
+# * Resolution: 800x1280
+# * PCLK Frequency: 60 MHz
+# * DSI Lane Bit Rate: 1 Gbps (using 2-Lane DSI configuration)
+# * Horizontal Timing (hsync_pulse_width=20, hsync_back_porch=20, hsync_front_porch=40)
+# * Vertical Timing (vsync_pulse_width=4, vsync_back_porch=8, vsync_front_porch=20)
+# ----------------------------------------------------------------------------------------------------------------------
+DriverChip(
+    "JC8012P4A1",
+    width=800,
+    height=1280,
+    hsync_back_porch=20,
+    hsync_pulse_width=20,
+    hsync_front_porch=40,
+    vsync_back_porch=8,
+    vsync_pulse_width=4,
+    vsync_front_porch=20,
+    pclk_frequency="60MHz",
+    lane_bit_rate="1Gbps",
+    swap_xy=cv.UNDEFINED,
+    color_order="RGB",
+    reset_pin=27,
+    initsequence=[
+        (0xE0, 0x00),
+        (0xE1, 0x93),
+        (0xE2, 0x65),
+        (0xE3, 0xF8),
+        (0x80, 0x01),
+        (0xE0, 0x01),
+        (0x00, 0x00),
+        (0x01, 0x39),
+        (0x03, 0x10),
+        (0x04, 0x41),
+        (0x0C, 0x74),
+        (0x17, 0x00),
+        (0x18, 0xD7),
+        (0x19, 0x00),
+        (0x1A, 0x00),
+        (0x1B, 0xD7),
+        (0x1C, 0x00),
+        (0x24, 0xFE),
+        (0x35, 0x26),
+        (0x37, 0x69),
+        (0x38, 0x05),
+        (0x39, 0x06),
+        (0x3A, 0x08),
+        (0x3C, 0x78),
+        (0x3D, 0xFF),
+        (0x3E, 0xFF),
+        (0x3F, 0xFF),
+        (0x40, 0x06),
+        (0x41, 0xA0),
+        (0x43, 0x14),
+        (0x44, 0x0B),
+        (0x45, 0x30),
+        (0x4B, 0x04),
+        (0x55, 0x02),
+        (0x57, 0x89),
+        (0x59, 0x0A),
+        (0x5A, 0x28),
+        (0x5B, 0x15),
+        (0x5D, 0x50),
+        (0x5E, 0x37),
+        (0x5F, 0x29),
+        (0x60, 0x1E),
+        (0x61, 0x1D),
+        (0x62, 0x12),
+        (0x63, 0x1A),
+        (0x64, 0x08),
+        (0x65, 0x25),
+        (0x66, 0x26),
+        (0x67, 0x28),
+        (0x68, 0x49),
+        (0x69, 0x3A),
+        (0x6A, 0x43),
+        (0x6B, 0x3A),
+        (0x6C, 0x3B),
+        (0x6D, 0x32),
+        (0x6E, 0x1F),
+        (0x6F, 0x0E),
+        (0x70, 0x50),
+        (0x71, 0x37),
+        (0x72, 0x29),
+        (0x73, 0x1E),
+        (0x74, 0x1D),
+        (0x75, 0x12),
+        (0x76, 0x1A),
+        (0x77, 0x08),
+        (0x78, 0x25),
+        (0x79, 0x26),
+        (0x7A, 0x28),
+        (0x7B, 0x49),
+        (0x7C, 0x3A),
+        (0x7D, 0x43),
+        (0x7E, 0x3A),
+        (0x7F, 0x3B),
+        (0x80, 0x32),
+        (0x81, 0x1F),
+        (0x82, 0x0E),
+        (0xE0, 0x02),
+        (0x00, 0x1F),
+        (0x01, 0x1F),
+        (0x02, 0x52),
+        (0x03, 0x51),
+        (0x04, 0x50),
+        (0x05, 0x4B),
+        (0x06, 0x4A),
+        (0x07, 0x49),
+        (0x08, 0x48),
+        (0x09, 0x47),
+        (0x0A, 0x46),
+        (0x0B, 0x45),
+        (0x0C, 0x44),
+        (0x0D, 0x40),
+        (0x0E, 0x41),
+        (0x0F, 0x1F),
+        (0x10, 0x1F),
+        (0x11, 0x1F),
+        (0x12, 0x1F),
+        (0x13, 0x1F),
+        (0x14, 0x1F),
+        (0x15, 0x1F),
+        (0x16, 0x1F),
+        (0x17, 0x1F),
+        (0x18, 0x52),
+        (0x19, 0x51),
+        (0x1A, 0x50),
+        (0x1B, 0x4B),
+        (0x1C, 0x4A),
+        (0x1D, 0x49),
+        (0x1E, 0x48),
+        (0x1F, 0x47),
+        (0x20, 0x46),
+        (0x21, 0x45),
+        (0x22, 0x44),
+        (0x23, 0x40),
+        (0x24, 0x41),
+        (0x25, 0x1F),
+        (0x26, 0x1F),
+        (0x27, 0x1F),
+        (0x28, 0x1F),
+        (0x29, 0x1F),
+        (0x2A, 0x1F),
+        (0x2B, 0x1F),
+        (0x2C, 0x1F),
+        (0x2D, 0x1F),
+        (0x2E, 0x52),
+        (0x2F, 0x40),
+        (0x30, 0x41),
+        (0x31, 0x48),
+        (0x32, 0x49),
+        (0x33, 0x4A),
+        (0x34, 0x4B),
+        (0x35, 0x44),
+        (0x36, 0x45),
+        (0x37, 0x46),
+        (0x38, 0x47),
+        (0x39, 0x51),
+        (0x3A, 0x50),
+        (0x3B, 0x1F),
+        (0x3C, 0x1F),
+        (0x3D, 0x1F),
+        (0x3E, 0x1F),
+        (0x3F, 0x1F),
+        (0x40, 0x1F),
+        (0x41, 0x1F),
+        (0x42, 0x1F),
+        (0x43, 0x1F),
+        (0x44, 0x52),
+        (0x45, 0x40),
+        (0x46, 0x41),
+        (0x47, 0x48),
+        (0x48, 0x49),
+        (0x49, 0x4A),
+        (0x4A, 0x4B),
+        (0x4B, 0x44),
+        (0x4C, 0x45),
+        (0x4D, 0x46),
+        (0x4E, 0x47),
+        (0x4F, 0x51),
+        (0x50, 0x50),
+        (0x51, 0x1F),
+        (0x52, 0x1F),
+        (0x53, 0x1F),
+        (0x54, 0x1F),
+        (0x55, 0x1F),
+        (0x56, 0x1F),
+        (0x57, 0x1F),
+        (0x58, 0x40),
+        (0x59, 0x00),
+        (0x5A, 0x00),
+        (0x5B, 0x10),
+        (0x5C, 0x05),
+        (0x5D, 0x50),
+        (0x5E, 0x01),
+        (0x5F, 0x02),
+        (0x60, 0x50),
+        (0x61, 0x06),
+        (0x62, 0x04),
+        (0x63, 0x03),
+        (0x64, 0x64),
+        (0x65, 0x65),
+        (0x66, 0x0B),
+        (0x67, 0x73),
+        (0x68, 0x07),
+        (0x69, 0x06),
+        (0x6A, 0x64),
+        (0x6B, 0x08),
+        (0x6C, 0x00),
+        (0x6D, 0x32),
+        (0x6E, 0x08),
+        (0xE0, 0x04),
+        (0x2C, 0x6B),
+        (0x35, 0x08),
+        (0x37, 0x00),
+        (0xE0, 0x00),
+    ]
+)
 # fmt: on

esphome/components/mqtt/mqtt_component.cpp

@@ -189,8 +189,7 @@ bool MQTTComponent::send_discovery_() {
         StringRef object_id = this->get_default_object_id_to_(object_id_buf);
         if (discovery_info.unique_id_generator == MQTT_MAC_ADDRESS_UNIQUE_ID_GENERATOR) {
           char friendly_name_hash[9];
-          sprintf(friendly_name_hash, "%08" PRIx32, fnv1_hash(this->friendly_name_()));
-          friendly_name_hash[8] = 0;  // ensure the hash-string ends with null
+          snprintf(friendly_name_hash, sizeof(friendly_name_hash), "%08" PRIx32, fnv1_hash(this->friendly_name_()));
           // Format: mac-component_type-hash (e.g. "aabbccddeeff-sensor-12345678")
           // MAC (12) + "-" (1) + domain (max 20) + "-" (1) + hash (8) + null (1) = 43
           char unique_id[MAC_ADDRESS_BUFFER_SIZE + ESPHOME_DOMAIN_MAX_LEN + 11];

esphome/components/ntc/ntc.cpp

@@ -23,7 +23,7 @@ void NTC::process_(float value) {
   double v = this->a_ + this->b_ * lr + this->c_ * lr * lr * lr;
   auto temp = float(1.0 / v - 273.15);
 
-  ESP_LOGD(TAG, "'%s' - Temperature: %.1f°C", this->name_.c_str(), temp);
+  ESP_LOGV(TAG, "'%s' - Temperature: %.1f°C", this->name_.c_str(), temp);
   this->publish_state(temp);
 }
 

esphome/components/resistance/resistance_sensor.cpp

@@ -39,7 +39,7 @@ void ResistanceSensor::process_(float value) {
   }
 
   res *= this->resistor_;
-  ESP_LOGD(TAG, "'%s' - Resistance %.1fΩ", this->name_.c_str(), res);
+  ESP_LOGV(TAG, "'%s' - Resistance %.1fΩ", this->name_.c_str(), res);
   this->publish_state(res);
 }
 

esphome/components/web_server/web_server.cpp

@@ -1178,11 +1178,7 @@ std::string WebServer::date_json_(datetime::DateEntity *obj, JsonDetail start_co
 
   // Format: YYYY-MM-DD (max 10 chars + null)
   char value[12];
-#ifdef USE_ESP8266
-  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d"), obj->year, obj->month, obj->day);
-#else
-  snprintf(value, sizeof(value), "%d-%02d-%02d", obj->year, obj->month, obj->day);
-#endif
+  buf_append_printf(value, sizeof(value), 0, "%d-%02d-%02d", obj->year, obj->month, obj->day);
   set_json_icon_state_value(root, obj, "date", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1241,11 +1237,7 @@ std::string WebServer::time_json_(datetime::TimeEntity *obj, JsonDetail start_co
 
   // Format: HH:MM:SS (8 chars + null)
   char value[12];
-#ifdef USE_ESP8266
-  snprintf_P(value, sizeof(value), PSTR("%02d:%02d:%02d"), obj->hour, obj->minute, obj->second);
-#else
-  snprintf(value, sizeof(value), "%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
-#endif
+  buf_append_printf(value, sizeof(value), 0, "%02d:%02d:%02d", obj->hour, obj->minute, obj->second);
   set_json_icon_state_value(root, obj, "time", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);
@@ -1304,13 +1296,8 @@ std::string WebServer::datetime_json_(datetime::DateTimeEntity *obj, JsonDetail
 
   // Format: YYYY-MM-DD HH:MM:SS (max 19 chars + null)
   char value[24];
-#ifdef USE_ESP8266
-  snprintf_P(value, sizeof(value), PSTR("%d-%02d-%02d %02d:%02d:%02d"), obj->year, obj->month, obj->day, obj->hour,
-             obj->minute, obj->second);
-#else
-  snprintf(value, sizeof(value), "%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour, obj->minute,
-           obj->second);
-#endif
+  buf_append_printf(value, sizeof(value), 0, "%d-%02d-%02d %02d:%02d:%02d", obj->year, obj->month, obj->day, obj->hour,
+                    obj->minute, obj->second);
   set_json_icon_state_value(root, obj, "datetime", value, value, start_config);
   if (start_config == DETAIL_ALL) {
     this->add_sorting_info_(root, obj);

esphome/core/helpers.cpp

@@ -487,19 +487,26 @@ static constexpr const char *BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                                             "abcdefghijklmnopqrstuvwxyz"
                                             "0123456789+/";
 
-// Helper function to find the index of a base64 character in the lookup table.
+// Helper function to find the index of a base64/base64url character in the lookup table.
 // Returns the character's position (0-63) if found, or 0 if not found.
+// Supports both standard base64 (+/) and base64url (-_) alphabets.
 // NOTE: This returns 0 for both 'A' (valid base64 char at index 0) and invalid characters.
 // This is safe because is_base64() is ALWAYS checked before calling this function,
 // preventing invalid characters from ever reaching here. The base64_decode function
 // stops processing at the first invalid character due to the is_base64() check in its
 // while loop condition, making this edge case harmless in practice.
 static inline uint8_t base64_find_char(char c) {
+  // Handle base64url variants: '-' maps to '+' (index 62), '_' maps to '/' (index 63)
+  if (c == '-')
+    return 62;
+  if (c == '_')
+    return 63;
   const char *pos = strchr(BASE64_CHARS, c);
   return pos ? (pos - BASE64_CHARS) : 0;
 }
 
-static inline bool is_base64(char c) { return (isalnum(c) || (c == '+') || (c == '/')); }
+// Check if character is valid base64 or base64url
+static inline bool is_base64(char c) { return (isalnum(c) || (c == '+') || (c == '/') || (c == '-') || (c == '_')); }
 
 std::string base64_encode(const std::vector<uint8_t> &buf) { return base64_encode(buf.data(), buf.size()); }