fix(tstest): preserve streaming console output and correctly buffer incomplete TAP lines

readme.hints.md

@@ -445,4 +445,49 @@ The protocol parser was fixed to correctly handle inline timing metadata:
 - Changed condition from `!simpleMatch[1].includes(':')` to check for simple key:value pairs
 - Excludes prefixed formats (META:, SKIP:, TODO:, EVENT:) while parsing simple formats like `time:250`
 
-This ensures timing metadata is correctly extracted and displayed in test results.
+This ensures timing metadata is correctly extracted and displayed in test results.
+
+## Streaming Console Output (Fixed)
+
+### Problem
+When tests use `process.stdout.write()` for streaming output (without newlines), each write was appearing on a separate line. This happened because:
+1. Child process stdout data events arrive as separate chunks
+2. `TapParser._processLog()` split on `\n` and processed each segment
+3. `testConsoleOutput()` used `console.log()` which added a newline to each call
+
+### Solution
+The streaming behavior is now preserved by:
+1. **Line buffering for TAP parsing**: Only buffer content that looks like TAP protocol messages
+2. **True streaming for console output**: Use `process.stdout.write()` instead of `console.log()` for partial lines
+3. **Intelligent detection**: `_looksLikeTapStart()` checks if content could be a TAP protocol message
+
+### Implementation Details
+
+**TapParser changes:**
+- Added `lineBuffer` property to buffer incomplete TAP protocol lines
+- Rewrote `_processLog()` to handle streaming correctly:
+  - Complete lines (with newline) are processed through protocol parser
+  - Incomplete lines that look like TAP are buffered
+  - Incomplete lines that don't look like TAP are streamed immediately
+- Added `_looksLikeTapStart()` helper to detect TAP protocol patterns
+- Added `_handleConsoleOutput()` to handle console output with proper streaming
+- Buffer is flushed on process exit
+
+**TsTestLogger changes:**
+- Added `testConsoleOutputStreaming()` method that uses `process.stdout.write()` in verbose mode
+- Added `logToTestFileRaw()` for writing to log files without adding newlines
+- In non-verbose mode, streaming content is appended to the last buffered entry
+
+**TapTestResult changes:**
+- Added `addLogLineRaw()` method that doesn't append newlines
+
+### Usage
+Tests can now use streaming output naturally:
+```typescript
+process.stdout.write("Loading");
+process.stdout.write(".");
+process.stdout.write(".");
+process.stdout.write(".\n");
+```
+
+This will correctly display as `Loading...` on a single line in verbose mode.