fix: accounts: a tag: query only matches account tags, not posting tags

Eg, `hledger accounts tag:t` lists only account a from this journal:

    account a  ; t:

    2025-01-01
        a          1
        b         -1  ; t:

hledger-lib/Hledger/Data/Journal.hs

@@ -98,6 +98,7 @@ module Hledger.Data.Journal (
   journalAccountTypes,
   journalAddAccountTypes,
   journalPostingsAddAccountTags,
+  journalPostingsKeepAccountTagsOnly,
   defaultBaseConversionAccount,
   -- journalPrices,
   journalBaseConversionAccount,
@@ -114,7 +115,7 @@ module Hledger.Data.Journal (
   -- * Tests
   samplejournal,
   samplejournalMaybeExplicit,
-  tests_Journal
+  tests_Journal,
   --
 )
 where
@@ -642,6 +643,13 @@ journalPostingsAddAccountTags :: Journal -> Journal
 journalPostingsAddAccountTags j = journalMapPostings addtags j
   where addtags p = p `postingAddTags` (journalInheritedAccountTags j $ paccount p)
 
+-- | Remove all tags from the journal's postings except those provided by their account.
+-- This is useful for the accounts report.
+-- It does not remove tag declarations from the posting comments.
+journalPostingsKeepAccountTagsOnly :: Journal -> Journal
+journalPostingsKeepAccountTagsOnly j = journalMapPostings keepaccounttags j
+  where keepaccounttags p = p{ptags=[]} `postingAddTags` (journalInheritedAccountTags j $ paccount p)
+
 -- | The account name to use for conversion postings generated by --infer-equity.
 -- This is the first account declared with type V/Conversion,
 -- or otherwise the defaultBaseConversionAccount (equity:conversion).

hledger/Hledger/Cli/Commands/Accounts.hs

@@ -62,12 +62,16 @@ accounts opts@CliOpts{rawopts_=rawopts, reportspec_=ReportSpec{_rsQuery=query,_r
       types = boolopt "types"    rawopts
       positions = boolopt "positions" rawopts
       directives = boolopt "directives" rawopts
+      -- Modified queries. These may not work with boolean queries (#2371).
       -- a depth limit will clip and exclude account names later, but we don't want to exclude accounts at this stage
       nodepthq = dbg4 "nodepthq" $ filterQuery (not . queryIsDepth) query
       -- just the acct: part of the query will be reapplied later, after clipping
       acctq = dbg4 "acctq" $ filterQuery queryIsAcct query
       dep = dbg4 "depth" $ queryDepth $ filterQuery queryIsDepth query
-      matchedused = dbg5 "matchedused" $ nub $ map paccount $ journalPostings $ filterJournalPostings nodepthq j
+      -- when finding accounts used by postings, we remove tags that were declared on the posting,
+      -- so that a tag: query will match account tags and not posting tags.
+      matchedused = dbg5 "matchedused" $ nub $ map paccount $ journalPostings $
+        filterJournalPostings nodepthq $ journalPostingsKeepAccountTagsOnly j
       matcheddeclared = dbg5 "matcheddeclared" $
         nub $
         filter (matchesAccountExtra (journalAccountType j) (journalInheritedAccountTags j) nodepthq) $

hledger/test/accounts.test

@@ -92,3 +92,14 @@ trade:A-B:A
 trade:A-B:B
 a
 b
+
+# ** 11. A tag: query only matches account tags, not posting tags.
+<
+account a  ; t:
+
+2025-01-01
+    a          1
+    b         -1  ; t:
+
+$ hledger -f- accounts tag:t
+a