config, mcp, gui: specs from sources, spec-blind suites, and the bugs they found

ledger-config: parse gets a sourced spec. A fiscal year starts on the
first of a month (IRS Pub. 538); tax_classification is read by whole
words (Treas. Reg. 301.7701-3, Schedule C instructions; "business corp"
no longer reads as an S corp, "corporation or S corporation" is refused);
duplicate or blank members and shared capital accounts are refused; a
negative or non-grammatical receipt threshold is refused; codes trimmed.
tests/spec_config.rs (65 spec-blind tests, 14 properties), fuzz target
fuzz_config_parse (weekly). Mutation: 55 of 55 viable caught (from 25/38).

The receipt policy moves to ledger-config, with one loader
(effective_receipt_policy) and one decimal grammar, so the server and
the viewer enforce and show the same rule (the viewer had its own: only
expense-like debits, a silent $25 default, and no config.json).

ledger-mcp: a module spec (MCP 2025-06-18 tools, JSON-RPC 2.0, the
operating contract). Amounts in are exactly -?digits[.digits]; a number
that is one account's code and another's id (vendors, classes alike) is
refused, not guessed; the threshold is validated at startup. Fixed:
add_line with a bad class journaled the line before refusing;
profit_and_loss_by_class ignored `class`; aging buckets said "0". A wire
in front of rmcp answers malformed JSON with -32700 and invalid requests
with -32600 and their id (rmcp dropped the first, omitted the id).
tests/spec_mcp.rs (26 spec-blind tests: every tool's result against its
own outputSchema, a random-call state machine checking the journal is
untouched by every refusal, amount grammar, previews, the receipt policy).

ledger-gui: money, accounting, and dollars never round (they rounded to
cents, banker's style); export file names avoid Windows device names,
trailing dots and spaces, empty names, and 255-byte overflow; specs on
attention, history, fuzzy search, and axis ticks.

ledger-core: the lifetime profit_and_loss is renamed unclosed_earnings
(docs/testing.md #3).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

docs/spec/sources/jsonrpc-2.0.md

@@ -0,0 +1,36 @@
+# JSON-RPC 2.0 Specification (jsonrpc.org/specification)
+
+Governs `ledger-mcp`'s wire protocol (MCP is JSON-RPC 2.0). Fetched
+2026-10-14.
+
+**5 Response object**
+
+> When a rpc call is made, the Server MUST reply with a Response, except
+> for in the case of Notifications. [...]
+>
+> result: This member is REQUIRED on success. This member MUST NOT exist
+> if there was an error invoking the method. [...]
+>
+> error: This member is REQUIRED on error. This member MUST NOT exist if
+> there was no error triggered during invocation. [...]
+>
+> id: This member is REQUIRED. It MUST be the same as the value of the id
+> member in the Request Object. If there was an error in detecting the id
+> in the Request object (e.g. Parse error/Invalid Request), it MUST be
+> Null.
+>
+> Either the result member or error member MUST be included, but both
+> members MUST NOT be included.
+
+**5.1 Error object**
+
+> code: A Number that indicates the error type that occurred. This MUST be
+> an integer. [...]
+>
+> | code | message | meaning |
+> |---|---|---|
+> | -32700 | Parse error | Invalid JSON was received by the server. |
+> | -32600 | Invalid Request | The JSON sent is not a valid Request object. |
+> | -32601 | Method not found | The method does not exist / is not available. |
+> | -32602 | Invalid params | Invalid method parameter(s). |
+> | -32603 | Internal error | Internal JSON-RPC error. |