Document public functions in parser_ext.h

diff --git a/src/common/parser_ext.h b/src/common/parser_ext.h
index d7f6b94..aa8314f 100644
--- a/src/common/parser_ext.h
+++ b/src/common/parser_ext.h
@@ -26,43 +26,84 @@ typedef int (*parsing_step_t)(void *, buffer_t *[2]);
 // the first buffer before reading from the second buffer.
 
 /**
- * Get the total remaining length readable from this pair of buffers.
- * TODO: finish docs
+ * Get the total number of remaining readable bytes from the concatenation of two buffers.
+ *
+ * @param[in] buffers Array of two pointers to buffers.
+ *
+ * @return the sum of remaining bytes in both buffers.
  */
 size_t dbuffer_get_length(buffer_t *buffers[2]);
 
 /**
- * TODO: docs.
+ * Check whether at least n bytes can be read from the concatenation of two buffers.
+ *
+ * @param[in] buffers Array of two pointers to buffers.
+ * @param[in] n       Number of bytes to check for.
+ *
+ * @return true if at least n bytes remain across both buffers, false otherwise.
  */
 bool dbuffer_can_read(buffer_t *buffers[2], size_t n);
 
 /**
- * TODO: docs.
+ * Read n bytes from the concatenation of two buffers into out.
+ * Bytes are consumed from the first buffer before the second.
+ *
+ * @param[in]  buffers Array of two pointers to buffers.
+ * @param[out] out     Destination buffer; must be at least n bytes long.
+ * @param[in]  n       Number of bytes to read.
+ *
+ * @return true on success, false if fewer than n bytes are available.
  */
 bool dbuffer_read_bytes(buffer_t *buffers[2], uint8_t *out, size_t n);
 
 /**
- * TODO: docs.
+ * Read a single byte from the concatenation of two buffers.
+ *
+ * @param[in]  buffers Array of two pointers to buffers.
+ * @param[out] out     Pointer to store the read byte.
+ *
+ * @return true on success, false if no bytes are available.
  */
 bool dbuffer_read_u8(buffer_t *buffers[2], uint8_t *out);
 
 /**
- * TODO: docs.
+ * Read a 16-bit unsigned integer from the concatenation of two buffers.
+ *
+ * @param[in]  buffers    Array of two pointers to buffers.
+ * @param[out] out        Pointer to store the read value.
+ * @param[in]  endianness Byte order (BE or LE).
+ *
+ * @return true on success, false if fewer than 2 bytes are available.
  */
 bool dbuffer_read_u16(buffer_t *buffers[2], uint16_t *out, endianness_t endianness);
 
 /**
- * TODO: docs.
+ * Read a 32-bit unsigned integer from the concatenation of two buffers.
+ *
+ * @param[in]  buffers    Array of two pointers to buffers.
+ * @param[out] out        Pointer to store the read value.
+ * @param[in]  endianness Byte order (BE or LE).
+ *
+ * @return true on success, false if fewer than 4 bytes are available.
  */
 bool dbuffer_read_u32(buffer_t *buffers[2], uint32_t *out, endianness_t endianness);
 
 /**
- * TODO: docs.
+ * Read a Bitcoin-style variable-length integer from the concatenation of two buffers.
+ * The encoding uses 1, 3, 5, or 9 bytes depending on the value prefix.
+ *
+ * @param[in]  buffers Array of two pointers to buffers.
+ * @param[out] out     Pointer to store the decoded value.
+ *
+ * @return true on success, false if there are not enough bytes available.
  */
 bool dbuffer_read_varint(buffer_t *buffers[2], uint64_t *out);
 
 /**
- * TODO: docs.
+ * Initialize a parser context, resetting the step counter and setting the state pointer.
+ *
+ * @param[out] parser_context Parser context to initialize.
+ * @param[in]  state          Pointer to the parser-specific state structure.
  */
 static inline void parser_init_context(parser_context_t *parser_context, void *state) {
     parser_context->cur_step = 0;
@@ -79,7 +120,18 @@ static inline void parser_init_context(parser_context_t *parser_context, void *s
 bool parser_consolidate_buffers(buffer_t *buffers[2], size_t max_size);
 
 /**
- * TODO: docs
+ * Execute a sequence of parsing steps, resuming from the current step in the parser context.
+ * Each step is called with the parser state and the pair of buffers. Execution advances to the
+ * next step when a step returns 1, and stops when a step returns 0 (needs more data) or -1
+ * (error).
+ *
+ * @param[in]     parsing_steps  Array of parsing step function pointers.
+ * @param[in]     n_steps        Number of steps in the array.
+ * @param[in,out] parser_context Parser context tracking the current step and state.
+ * @param[in]     buffers        Array of two pointers to buffers containing the data to parse.
+ * @param[in]     pic_fn         PIC address-translation function, or NULL if not needed.
+ *
+ * @return 1 if all steps completed, 0 if more data is needed, -1 on parsing error.
  */
 int parser_run(const parsing_step_t *parsing_steps,
                size_t n_steps,