feat(prompt): structured options with name|key|description tuples and jq-style dynamic mapping

- parse_structured_options: parse name|key|description tuples from <<var [...]
- parse_dynamic_mapping: parse pipe + {name:path,key:path,desc:path} syntax
- apply_jq_mapping: map response data to structured picker items
- handle_prompt_variables: integrated both static tuples and dynamic mapping
- highlight: PostePromptOptSep, PostePromptMapping{Field,Colon,Path} groups
- completion: prompt_mapping context for field name completion
- docs: new Prompt Variables section in README with full syntax examples
- tests: 22 test cases covering all parsing and mapping scenarios

Author: lex

PROMPT_ENHANCE_PLAN.md

@@ -369,6 +369,80 @@ Requires **blink.cmp**. Auto-registers as `poste_sql` source provider.
 :PosteSQLCmpStatus  " SQL completion status
 ```
 
+## Prompt Variables
+
+Prompt variables allow interactive input when running a request. When you execute a request with `<<` directives, Poste will prompt you for values before sending.
+
+### Text Input
+
+```
+<<username
+```
+
+Shows a text input prompt for `username`. Press `<Enter>` to confirm or `<Esc>` to cancel.
+
+### Selection from List (Simple Strings)
+
+```
+<<method [GET, POST, PUT, DELETE]
+```
+
+Shows a picker with the listed options. Selecting one substitutes `@method = <selected>`.
+
+### Selection with Display Name, Key, and Description
+
+```
+<<method [GET|get|Send a GET request, POST|post|Send a POST request, PUT|put|Send a PUT request]
+```
+
+Each option is formatted as `name|key|description`:
+- **name** — shown in the picker
+- **key** — the actual value substituted into the request
+- **description** — secondary text displayed alongside the name
+
+Picker shows:
+```
+  GET    Send a GET request
+  POST   Send a POST request
+  PUT    Send a PUT request
+```
+
+Selecting `GET` writes `@method = get` (the key, not the display name) into the request.
+
+Two-field form (name|key, no description):
+```
+<<method [GET|get, POST|post]
+```
+
+### Dynamic Options from Another Request
+
+```http
+### Get commits
+GET https://api.github.com/repos/folke/snacks.nvim/commits
+
+### Send email
+<<email [{{1.response.body | {name: .[].commit.author.name, key: .[].commit.author.email, desc: .[].commit.author.name} }}]
+
+POST https://httpbin.org/post
+Content-Type: application/json
+
+{"email": "{{email}}"}
+```
+
+The pipe `|` separates the response reference from a **jq-style mapping expression**:
+
+```
+{{<request_ref> | {name: <path>, key: <path>, desc: <path>} }}
+```
+
+- `<request_ref>` — standard cross-request reference (e.g., `1.response.body`)
+- `<path>` — dot-separated path into the response, using `[]` for array iteration (jq-compatible)
+
+If the response body is already in `{name, key, description}` format, the mapping can be omitted:
+```
+<<email [{{1.response.body}}]
+```
+
 ## SQL Features
 
 ### Connection management

README.md

@@ -4,6 +4,10 @@
 ### jq
 GET https://api.github.com/repos/jqlang/jq/commits?per_page=5
 
+### prompt enhance
+<<method [ {{jq.response.body | {name: .[].commit.author.name, key: .[].author.id, desc: .[].commit.author.email} }} ]
+GET https://httpbin.org/get?method={{method}}
+
 ### Select items
 @key = fruit
 <<item [{{jq.response.body.[].parents[].sha}}]
@@ -20,6 +24,10 @@ GET {{base_url}}/get?fruit={{fruit}}
 <<method [GET, POST, PUT, DELETE]
 GET https://httpbin.org/get?method={{method}}
 
+### Static Options
+<<method [GET|get|get something, POST|post|post something, PUT|put|put something, DELETE|del|delete obj]
+GET https://httpbin.org/get?method={{method}}
+
 ### Text Input
 <<username
 GET https://httpbin.org/get?user={{username}}

examples/http/dynamic_prompts.feature.http

@@ -235,6 +235,7 @@ M._test = {
   mime_types = data.mime_types,
   header_values = data.header_values,
   magic_var_defs = data.magic_var_defs,
+  prompt_mapping_fields = data.prompt_mapping_fields,
 }
 
 return M

lua/poste/http/completion.lua

@@ -116,6 +116,10 @@ local function detect_context(line_before_cursor, buf, cursor_line, cursor_col)
   if last_open and (not last_close or last_close > last_open) then
     -- Cursor is inside an unclosed {{...}}
     local after_open = line_before_cursor:sub(#line_before_cursor - last_open + 2)
+    -- Check if this is a prompt mapping context (contains | {)
+    if after_open:match("|%s*{%s*$") or after_open:match("|%s*{%s*%w*$") then
+      return "prompt_mapping", after_open
+    end
     return "variable", after_open
   end
 

lua/poste/http/context_detector.lua

@@ -875,4 +875,14 @@ M.script_api_docs = {
   },
 }
 
+---------------------------------------------------------------------------
+-- Prompt mapping fields (for jq-style mapping completion)
+---------------------------------------------------------------------------
+M.prompt_mapping_fields = {
+  { name = "name", desc = "Display name in picker" },
+  { name = "key", desc = "Substitution value" },
+  { name = "desc", desc = "Description shown in picker (alias for description)" },
+  { name = "description", desc = "Description shown in picker" },
+}
+
 return M

lua/poste/http/data.lua

@@ -64,6 +64,10 @@ function M.setup()
     { "PostePromptMarker", "PreProc" },
     { "PostePromptVar",    "PosteVarDef" },
     { "PostePromptOpts",   "String" },
+    { "PostePromptOptSep", "Delimiter" },
+    { "PostePromptMappingField", "Type" },
+    { "PostePromptMappingColon", "Operator" },
+    { "PostePromptMappingPath",  "Identifier" },
     { "PostePreScript",    "PreProc" },
     { "PosteAssertion",    "PreProc" },
     { "PosteScriptMarker", "Special" },
@@ -193,6 +197,7 @@ function M.setup()
     "PosteImport", "PosteImportPath", "PosteImportAliasOpt", "PosteImportAlias",
     "PosteRun", "PosteRunTarget", "PosteRunVarDef", "PosteRunVarAssign", "PosteRunVarValue",
     "PostePromptMarker", "PostePromptVar", "PostePromptOpts",
+    "PostePromptOptSep", "PostePromptMappingField", "PostePromptMappingColon", "PostePromptMappingPath",
     "PostePreScript", "PosteAssertion", "PosteScriptMarker", "PosteExternalScript",
     "PosteFileUpload", "PosteFileRef",
     "PosteJsonString", "PosteJsonNumber", "PosteJsonBoolean", "PosteJsonNull",

lua/poste/http/highlights.lua

@@ -351,6 +351,9 @@ function M.get_items_for_context(line_before_cursor, buf, cursor_line, cursor_co
     if values then
       items = M.build_items(values, KIND_VALUE)
     end
+  elseif ctx == "prompt_mapping" then
+    items = M.build_keyword_items(data.prompt_mapping_fields, KIND_PROPERTY)
+    return items
   end
 
   return items