--- title: "Changes to Send Message" method: POST path: "/chats/{chatId}/messages" --- # Changes to Send Message `POST /chats/{chatId}/messages` > Every recorded change to this endpoint, newest first. ## Timeline Changed in 17 of 34 revisions. - **2026-08-27** `3cf5debd6cf4` — 1 breaking, 3 warning, 5 info - **2026-08-26** `76c7f743f0e9` — 2 info - **2026-07-31** `ca413e5ca710` — 1 info - **2026-07-30** `da68370a2aea` — 21 breaking, 13 warning, 29 info - **2026-07-21** `b53921245779` — 1 warning, 1 info - **2026-04-30** `670c302548ec` — 1 warning, 5 info - **2026-03-06** `b73ab7a6f317` — 1 info - **2026-03-06** `79811cd54faa` — 2 warning, 2 info - **2026-02-23** `8b21bf5afcfa` — 3 warning, 2 info - **2026-01-20** `86302d0793b1` — 6 breaking, 6 warning, 14 info - **2025-12-01** `417773084cbe` — 1 warning, 2 info - **2025-10-23** `bcf554284606` — 9 info - **2025-09-24** `fd6d8c3bee8a` — 1 info - **2025-09-17** `71c04d617e58` — 2 info - **2025-09-12** `e9f83fb57a16` — 1 breaking, 5 info - **2025-08-29** `90f1f1e3f7eb` — 1 info - **2025-08-24** `3521652a43a7` — 11 breaking, 13 warning, 25 info ## Changes - **2026-08-27** `3cf5debd6cf4` — 1 breaking, 3 warning, 5 info - the `attachments/items/` request property type/format changed from `object`/`` to ``/`` (media type: application/json) - removed the request property `attachments/items/url` (media type: application/json) - removed the request property `attachments/items/url` (media type: application/x-www-form-urlencoded) - removed the request property `attachments/items/url` (media type: multipart/form-data) - added `subschema #1, subschema #2` to the `attachments/items/` request property `anyOf` list (media type: application/json) - added `subschema #1, subschema #2` to the `attachments/items/` request property `anyOf` list (media type: application/x-www-form-urlencoded) - added `subschema #1, subschema #2` to the `attachments/items/` request property `anyOf` list (media type: multipart/form-data) - the `attachments/items/` request property type/format was generalized from `object`/`` to ``/`` (media type: application/x-www-form-urlencoded) - the `attachments/items/` request property type/format was generalized from `object`/`` to ``/`` (media type: multipart/form-data) - **2026-08-26** `76c7f743f0e9` — 2 info - added the optional property `parts/items/oneOf[subschema #7]/suggestedPermissions/items/toolDisplayName` to the response with the `200` status - added the optional property `parts/items/oneOf[subschema #7]/toolDisplayName` to the response with the `200` status - **2026-07-31** `ca413e5ca710` — 1 info - added `subschema #4` to the `parts/items/oneOf[subschema #8]/data` response property `anyOf` list for the response status `200` - **2026-07-30** `da68370a2aea` — 21 breaking, 13 warning, 29 info - for the `path` request parameter `chatId`, the minLength was increased from `0` to `1` - removed `subschema #1, subschema #2, subschema #3` from the `skills/items/` request property `anyOf` list - removed the enum value `v0-auto` of the request property `modelConfiguration/modelId` - the `message` request property's minLength was increased from `0` to `1` - response property `authorId` list-of-types was widened by adding types `null` to media type `application/json` of response `200` - removed the required property `apiUrl` from the response with the `200` status - removed the required property `error` from the response with the `401` status - removed the required property `error` from the response with the `403` status - removed the required property `error` from the response with the `404` status - removed the required property `error` from the response with the `422` status - removed the required property `error` from the response with the `500` status - removed the required property `favorite` from the response with the `200` status - removed the required property `messages` from the response with the `200` status - removed the required property `metadata` from the response with the `200` status - removed the required property `object` from the response with the `200` status - removed the required property `permissions` from the response with the `200` status - removed the required property `privacy` from the response with the `200` status - removed the required property `shareable` from the response with the `200` status - removed the required property `text` from the response with the `200` status - removed the required property `url` from the response with the `200` status - removed the required property `webUrl` from the response with the `200` status - removed the request property `action` - removed the request property `attachedSkillIds` - removed the request property `modelConfiguration/thinking` - removed the request property `responseMode` - removed the request property `system` - removed the optional property `demo` from the response with the `200` status - removed the optional property `files` from the response with the `200` status - removed the optional property `latestVersion` from the response with the `200` status - removed the optional property `modelConfiguration` from the response with the `200` status - removed the optional property `name` from the response with the `200` status - removed the optional property `projectId` from the response with the `200` status - removed the optional property `title` from the response with the `200` status - removed the optional property `vercelProjectId` from the response with the `200` status - api operation id `chats.sendMessage` removed and replaced with `messages.send` - the endpoint scheme security `apiKey` was removed from the API - api tag `Messages` added - api tag `chats` removed - added the new optional request property `systemPrompt` - added the media type `application/x-www-form-urlencoded` to the request body - …23 more - **2026-07-21** `b53921245779` — 1 warning, 1 info - added the new `v0-opus-4.7-fast` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new optional request property `skills` - **2026-04-30** `670c302548ec` — 1 warning, 5 info - added the new `v0-opus-4.7` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new optional request property `action` - added the new optional request property `attachedSkillIds` - request property `modelConfiguration/modelId` reactivated - added the optional property `vercelProjectId` to the response with the `200` status - response property `modelConfiguration/modelId` reactivated - **2026-03-06** `b73ab7a6f317` — 1 info - added the new optional request property `mcpServerIds` - **2026-03-06** `79811cd54faa` — 2 warning, 2 info - added the new `design-mode` enum value to the `messages/items/type` response property for the response status `200` - added the new `v0-auto` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-auto` enum value to the request property `modelConfiguration/modelId` - added the required property `metadata` to the response with the `200` status - **2026-02-23** `8b21bf5afcfa` — 3 warning, 2 info - added the new `cloned-repo` enum value to the `messages/items/type` response property for the response status `200` - added the new `manual-commit` enum value to the `messages/items/type` response property for the response status `200` - added the new `v0-max-fast` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-max-fast` enum value to the request property `modelConfiguration/modelId` - removed the `unknown` enum value from the `messages/items/finishReason` response property for the response status `200` - **2026-01-20** `86302d0793b1` — 6 breaking, 6 warning, 14 info - removed the enum value `v0-1.5-lg` of the request property `modelConfiguration/modelId` - removed the enum value `v0-1.5-md` of the request property `modelConfiguration/modelId` - removed the enum value `v0-1.5-sm` of the request property `modelConfiguration/modelId` - removed the enum value `v0-gpt-5` of the request property `modelConfiguration/modelId` - removed the enum value `v0-opus-4.5` of the request property `modelConfiguration/modelId` - removed the required property `messages/items/experimental_content/items/anyOf[subschema #2]/prefixItems[subschema #2]/~standard` from the response with the `200` status - added the new `answered-questions` enum value to the `messages/items/type` response property for the response status `200` - added the new `fix-cve` enum value to the `messages/items/type` response property for the response status `200` - added the new `pull-changes` enum value to the `messages/items/type` response property for the response status `200` - added the new `v0-max` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-mini` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-pro` enum value to the `modelConfiguration/modelId` response property for the response status `200` - the `modelId` request property default value changed from `v0-1.5-md` to `v0-pro` - added the new `v0-max` enum value to the request property `modelConfiguration/modelId` - added the new `v0-mini` enum value to the request property `modelConfiguration/modelId` - added the new `v0-pro` enum value to the request property `modelConfiguration/modelId` - the `modelId` response's property default value changed from `v0-1.5-md` to `v0-pro` for the status `200` - removed the `v0-1.5-lg` enum value from the `modelConfiguration/modelId` response property for the response status `200` - removed the `v0-1.5-md` enum value from the `modelConfiguration/modelId` response property for the response status `200` - removed the `v0-1.5-sm` enum value from the `modelConfiguration/modelId` response property for the response status `200` - removed the `v0-gpt-5` enum value from the `modelConfiguration/modelId` response property for the response status `200` - removed the `v0-opus-4.5` enum value from the `modelConfiguration/modelId` response property for the response status `200` - added the required property `messages/items/experimental_content/items/anyOf[subschema #2]/prefixItems[subschema #2]/apply` to the response with the `200` status - added the required property `messages/items/experimental_content/items/anyOf[subschema #2]/prefixItems[subschema #2]/exactOptional` to the response with the `200` status - added the required property `messages/items/experimental_content/items/anyOf[subschema #2]/prefixItems[subschema #2]/toJSONSchema` to the response with the `200` status - added the required property `messages/items/experimental_content/items/anyOf[subschema #2]/prefixItems[subschema #2]/with` to the response with the `200` status - **2025-12-01** `417773084cbe` — 1 warning, 2 info - added the new `v0-opus-4.5` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new optional request property `system` - added the new `v0-opus-4.5` enum value to the request property `modelConfiguration/modelId` - **2025-10-23** `bcf554284606` — 9 info - added the optional property `messages/items/attachments` to the response with the `200` status - added `subschema #1, subschema #2` to the `messages/items/experimental_content/items/` response property `anyOf` list for the response status `200` - removed `subschema #1, subschema #2` from the `messages/items/experimental_content/items/` response property `anyOf` list for the response status `200` - the `createdAt` response's property pattern `^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$` was added for the status `200` - the `latestVersion/createdAt` response's property pattern `^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$` was added for the status `200` - the `latestVersion/updatedAt` response's property pattern `^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$` was added for the status `200` - the `messages/items/updatedAt` response's property pattern `^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$` was added for the status `200` - added 'propertyNames' constraint to the `files/items/meta` response property for the status `200` - added the required property `messages/items/authorId` to the response with the `200` status - **2025-09-24** `fd6d8c3bee8a` — 1 info - added the optional property `latestVersion/screenshotUrl` to the response with the `200` status - **2025-09-17** `71c04d617e58` — 2 info - the `modelId` request property default value `v0-1.5-md` was added - the `modelId` response's property default value `v0-1.5-md` was added for the status `200` - **2025-09-12** `e9f83fb57a16` — 1 breaking, 5 info - the response property `modelConfiguration/modelId` became optional for the status `200` - the request property `modelConfiguration/modelId` became optional - request property `modelConfiguration/modelId` deprecated - added the optional property `messages/items/parentId` to the response with the `200` status - response property `modelConfiguration/modelId` deprecated - added the required property `permissions` to the response with the `200` status - **2025-08-29** `90f1f1e3f7eb` — 1 info - added the new `experimental_stream` enum value to the request property `responseMode` - **2025-08-24** `3521652a43a7` — 11 breaking, 13 warning, 25 info - the request property `modelConfiguration/modelId` became required - removed the enum value `experimental_stream` of the request property `responseMode` - removed the enum value `v0-auto` of the request property `modelConfiguration/modelId` - removed the enum value `v0-max` of the request property `modelConfiguration/modelId` - removed the enum value `v0-max-fast` of the request property `modelConfiguration/modelId` - removed the enum value `v0-mini` of the request property `modelConfiguration/modelId` - removed the enum value `v0-pro` of the request property `modelConfiguration/modelId` - removed 'propertyNames' constraint from the `files/items/meta` response property for the status `200` - removed the required property `messages/items/authorId` from the response with the `200` status - removed the required property `metadata` from the response with the `200` status - removed the required property `permissions` from the response with the `200` status - removed the request property `action` - removed the request property `attachedSkillIds` - removed the request property `mcpServerIds` - removed the request property `system` - removed the optional property `latestVersion/screenshotUrl` from the response with the `200` status - removed the optional property `messages/items/attachments` from the response with the `200` status - removed the optional property `messages/items/parentId` from the response with the `200` status - removed the optional property `vercelProjectId` from the response with the `200` status - added the new `unknown` enum value to the `messages/items/finishReason` response property for the response status `200` - added the new `v0-1.5-lg` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-1.5-md` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-1.5-sm` enum value to the `modelConfiguration/modelId` response property for the response status `200` - added the new `v0-gpt-5` enum value to the `modelConfiguration/modelId` response property for the response status `200` - the `modelId` request property default value `v0-pro` was removed - added the new `v0-1.5-lg` enum value to the request property `modelConfiguration/modelId` - added the new `v0-1.5-md` enum value to the request property `modelConfiguration/modelId` - added the new `v0-1.5-sm` enum value to the request property `modelConfiguration/modelId` - added the new `v0-gpt-5` enum value to the request property `modelConfiguration/modelId` - added `subschema #1, subschema #2` to the `messages/items/experimental_content/items/` response property `anyOf` list for the response status `200` - removed `subschema #1, subschema #2` from the `messages/items/experimental_content/items/` response property `anyOf` list for the response status `200` - the response property `modelConfiguration/modelId` became required for the status `200` - the `modelId` response's property default value `v0-pro` was removed for the status `200` - removed the `answered-questions` enum value from the `messages/items/type` response property for the response status `200` - removed the `cloned-repo` enum value from the `messages/items/type` response property for the response status `200` - removed the `design-mode` enum value from the `messages/items/type` response property for the response status `200` - removed the `fix-cve` enum value from the `messages/items/type` response property for the response status `200` - removed the `manual-commit` enum value from the `messages/items/type` response property for the response status `200` - removed the `pull-changes` enum value from the `messages/items/type` response property for the response status `200` - removed the `v0-auto` enum value from the `modelConfiguration/modelId` response property for the response status `200` - …9 more --- [Operation](https://skmtc.dev/vercel/apis/v0-platform-api-beta/docs/chats/:chatId/messages/post.md) · [API](https://skmtc.dev/vercel/apis/v0-platform-api-beta.md) · [Page](https://skmtc.dev/vercel/apis/v0-platform-api-beta/changes/chats/:chatId/messages/post)