Fix silent drop of .jsonl files in project miner

mempalace/miner.py:READABLE_EXTENSIONS contained `.json` but not
`.jsonl`. Every jsonl file encountered in a mined directory was
silently skipped at miner.py:722:

    if filepath.suffix.lower() not in READABLE_EXTENSIONS:
        continue

Claude Code transcripts, ChatGPT exports, and every other tool writing
line-delimited JSON ship as `.jsonl`. Users running `mempalace mine`
against a directory of transcripts saw the command complete with no
error and no log line — and their conversations never reached the
palace. Silent data loss.

Adding `.jsonl` to the whitelist alongside `.json`. jsonl is text
line-by-line; the existing chunking pipeline handles it the same way
it handles any other text file.

Tests: tests/test_miner_jsonl_visibility.py

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_miner_jsonl_visibility.py

@@ -0,0 +1,69 @@
+"""TDD: miner.py must not silently drop .jsonl files.
+
+The project miner (mempalace.miner.scan_project) walks a directory and
+keeps only files whose suffix is in READABLE_EXTENSIONS. The whitelist
+contains `.json` but NOT `.jsonl`. Every ChatGPT export, Claude Code
+transcript, or any other jsonl transcript dumped into a project
+directory is silently dropped with no user-visible output.
+
+Two paths to fix this, both tested here:
+
+  1. READABLE_EXTENSIONS must include `.jsonl` so the file is at least
+     readable as text (jsonl is line-delimited JSON — each line is
+     already valid text for embedding).
+  2. OR scan_project must surface skipped .jsonl files to the user so
+     they know to use `--mode convos`.
+
+We test (1) — include .jsonl in READABLE_EXTENSIONS. This matches how
+`.json` is already handled: the miner doesn't care what the structure
+is, it chunks the text.
+
+Written BEFORE the fix.
+"""
+
+import tempfile
+from pathlib import Path
+
+from mempalace.miner import READABLE_EXTENSIONS, scan_project
+
+
+class TestJsonlNotSilentlySkipped:
+    def test_jsonl_in_readable_extensions(self):
+        """`.jsonl` must be in the readable-extensions whitelist.
+
+        `.json` is already there (see mempalace/miner.py:30). `.jsonl`
+        is conceptually the same thing — line-delimited JSON — and all
+        of Claude Code's transcripts, ChatGPT exports, and similar
+        tooling writes `.jsonl`. Excluding it silently drops user data.
+        """
+        assert ".jsonl" in READABLE_EXTENSIONS, (
+            "mempalace/miner.py:READABLE_EXTENSIONS contains `.json` "
+            "but NOT `.jsonl`. Every jsonl file in a mined project is "
+            "silently skipped at miner.py:722 "
+            "(`if filepath.suffix.lower() not in READABLE_EXTENSIONS: "
+            "continue`). This causes the 'convos not being saved' bug "
+            "reported by users — the hook fires `mempalace mine`, the "
+            "miner walks the directory, skips every .jsonl file, exits "
+            "cleanly. No warning, no log line, user sees nothing wrong. "
+            "Add `.jsonl` to READABLE_EXTENSIONS."
+        )
+
+    def test_scan_project_picks_up_jsonl_file(self):
+        """scan_project should find .jsonl files in the target dir."""
+        with tempfile.TemporaryDirectory() as tmp:
+            tmpdir = Path(tmp)
+            jsonl_path = tmpdir / "transcript.jsonl"
+            jsonl_path.write_text(
+                '{"role": "user", "content": "hello"}\n'
+                '{"role": "assistant", "content": "hi there"}\n'
+                '{"role": "user", "content": "how do I install this"}\n'
+                '{"role": "assistant", "content": "pip install mempalace"}\n'
+            )
+
+            found = scan_project(str(tmpdir))
+            found_names = [p.name for p in found]
+            assert "transcript.jsonl" in found_names, (
+                "scan_project silently dropped transcript.jsonl. "
+                f"Returned: {found_names}. Users placing transcript "
+                "exports in a project directory expect them to be mined."
+            )