The kon-mcp stdio server is documented as "read-only, no auth, local-only"
but until now opened the SQLite store via `kon_storage::init`, which returns
a writable pool and runs migrations. Read-only-ness was enforced only by the
exposed tool surface (list_transcripts, get_transcript, search_transcripts,
list_tasks); a future bug or a malformed dispatch could escape into a write
against the user's primary database.
Add `kon_storage::init_readonly` that opens with `SqliteConnectOptions
::read_only(true)` and `create_if_missing(false)`, no migrations. The
constraint is now structural — SQLite rejects writes at the connection
level regardless of which handler runs.
- New `init_readonly(path)` in crates/storage/src/database.rs.
- Re-exported from kon_storage.
- crates/mcp/src/main.rs switched over and updated startup banner.
- Two tests: writes fail on the read-only pool, reads succeed; opening a
non-existent DB returns an error instead of silently creating one.
https://claude.ai/code/session_0189xUb6ie6t9qHkzatGZ9Rb
Regression surfaced by the batch review: commit 8400128 switched
list_transcripts from unwrap_or_default to map_err(-32602). This
correctly errors on malformed payloads but also rejected the common
case where a client omits the 'arguments' field entirely — which
arrives as Value::Null, and serde_json::from_value does not
deserialise Null into a struct.
Short-circuits the Null case to Args::default() before attempting
deserialisation. Genuine shape mismatches ("limit": "twenty")
still return -32602 as the previous test asserts.
New regression test: tools/call with list_transcripts and no
arguments key must return a successful response.
MAJOR from the 2026-04-22 review (crates/mcp/src/lib.rs:188-195):
the handler called serde_json::from_value(args).unwrap_or_default(),
so a request like { "limit": "twenty" } silently became the default
limit of 20. Every other tool handler in this file map_errs to
-32602 Invalid arguments; this one was the outlier.
Switches to the same map_err pattern. Empty params still
deserialise cleanly to Args::default (via #[serde(default)] on the
Option<i64> field), so callers that send no args are unaffected —
only genuinely malformed shapes now error.
Regression test: tools/call with list_transcripts and a
string-typed limit must return code -32602 with an "Invalid
arguments" message.
MAJOR from the 2026-04-22 review (crates/mcp/src/main.rs:26-30): the
stdio transport logged malformed JSON lines to stderr and continued
without sending any JSON-RPC response. Clients saw silence instead of
the -32700 Parse Error they could key off. handle_message has a
parse-error branch for shape mismatch, but it never ran for bytes
that failed to parse as JSON at all.
Exposes a new public helper kon_mcp::parse_error_response(detail)
that mirrors the existing internal error_response pattern, filling
id with null per JSON-RPC 2.0 §5.1 (parse error, no id recoverable).
main.rs now writes that response out before continuing the read
loop.
Regression test on the helper asserts: jsonrpc "2.0", id null,
code -32700, message starts with "Parse error" and includes the
underlying serde detail.
QC smoke sweep flagged two clippy -D warnings lints in code this branch
introduced:
- crates/core/src/process_watch.rs — collapsible_if on the meeting-pattern
match loop, merged the two conditions with &&.
- crates/mcp/src/lib.rs — let-else on the id unwrap that short-circuits a
notification, switched to ? since handle_message already returns Option.
All other clippy lints under -D warnings (audio/capture, hotkey/linux,
storage/file_storage, diagnostics, the duplicate-detection helpers in
live.rs) predate this branch and are out of scope.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
New workspace binary crates/mcp exposes Kon's SQLite store to external
agents (Claude desktop, Cline, any MCP client) without running the Tauri
app. Newline-delimited JSON-RPC 2.0 on stdio, MCP protocol 2024-11-05.
Tools shipped (all read-only):
- list_transcripts — recent transcript summaries, limit 1..200 default 20
- get_transcript — full text + metadata by id
- search_transcripts — FTS5-backed query, limit 1..100 default 20
- list_tasks — all tasks (open + done)
No writes. The Tauri app remains the only writer; kon-mcp just opens the
same SQLite file (via kon_storage::init) and reads. Logs land on stderr to
keep stdout clean for the JSON-RPC stream. Smoke-tested end-to-end with
initialize + tools/list over a pipe.
Wire into an MCP client with:
{ "mcpServers": { "kon": { "command": "/path/to/kon-mcp" } } }
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
