Summary

Three compounding bugs in extract_media (gateway/platforms/base.py) caused MEDIA:/path tags to silently fail on Discord and likely other platforms. Discovered while trying to attach an HTML file from chat.

Bugs Fixed

1. \s* after MEDIA: consumes newlines, bridges to later MEDIA: tag

When the agent's response contains MEDIA: as conversational text on one line AND a real MEDIA:/path tag on a later line, the old regex bridges across the gap and the path slot falls through to the |\S+ fallback — capturing the literal MEDIA: prefix as part of the path.

Repro:

response = "Test 3 PNG via MEDIA:\n\nMEDIA:/tmp/foo.png"
BasePlatformAdapter.extract_media(response)
# Old: [('MEDIA:/tmp/foo.png', False)]   ← prefix glued on
# New: [('/tmp/foo.png', False)]

Downstream send_multiple_images then checks os.path.exists("MEDIA:/tmp/foo.png") → False → logs Skipping missing image.

Fix: change \s* to [^\S\n]* (horizontal whitespace only).

2. |\S+ final fallback truncates paths with spaces

The |\S+ catch-all in the path alternatives truncated paths containing spaces at the first whitespace character. For example, an Obsidian vault path:

response = 'MEDIA:/Users/alex/Obsidian/Ace Place/Engineering/foo.html'
# Old: matched '/Users/alex/Obsidian/Ace'  ← truncated, then File not found
# Old gateway log: '[Discord] Failed to send media (): File not found: /Users/alex/Obsidian/Ace'

It also enabled bug #1 by allowing pathological captures of MEDIA:/... text.

Fix: drop |\S+ entirely. Unrecognized extensions now require quoting (MEDIA:"/path/anything"). Recognized extensions still support unquoted paths with internal spaces via the existing (?:[^\S\n]+\S+)*? continuation.

3. Extension allowlist excluded common developer text formats

.html, .svg, .md, .json, .yaml, .xml, .log, source code (.py/.js/.ts/.jsx/.tsx), shell (.sh/.bash/.zsh), and config (.toml/.ini/.conf/.cfg/.env) were all rejected — MEDIA: tags for these file types appeared as plain text in chat instead of being uploaded as attachments.

Fix: expand the allowlist to cover these formats.

Bonus fix: streaming dispatch path discards cleaned text

gateway/run.py:~10015 was dropping the cleaned-text return value from extract_media/extract_images on the floor:

# BEFORE
media_files, _ = adapter.extract_media(response)        # discards cleaned
_, cleaned = adapter.extract_images(response)            # uses RAW response
local_files, _ = adapter.extract_local_files(cleaned)   # MEDIA: never stripped

This caused extract_local_files to scan raw MEDIA: text in the streaming dispatch path, producing false-positive bare-path matches.

Fix: chain cleaned text through the extractors in order, matching the non-streaming path in base.py:~2983.

Testing

Added regression tests in tests/gateway/test_platform_base.py:

• test_prose_media_word_does_not_bridge_to_later_tag — bug Terminal tool #1
• test_html_extension_is_allowlisted — bug Architecture planning #3 (parameterized over 23 extensions)
• test_unquoted_path_with_unrecognized_extension_is_left_alone — bug Support passing morph snapshot id #2 + new behavior
• test_quoted_path_with_unrecognized_extension_still_works — verifies the quoted-path escape hatch still works for unusual extensions
• test_path_with_spaces_in_allowlisted_extension_still_works — confirms existing unquoted-spaces support didn't regress

All 95 tests in test_platform_base.py pass. Three pre-existing failures in test_tts_media_routing.py are unrelated (_thread_metadata_for_source attribute missing on a mock) — they fail identically on clean origin/main.

Backwards compatibility

• All existing tests pass unchanged.
• The one behavior change for callers: unquoted MEDIA:/path.unknownext (unrecognized extension) now leaves the tag in user-visible text instead of silently extracting a truncated/corrupted path. Quoted paths (MEDIA:"/path.unknownext") continue to work for the escape-hatch case. Net result: a clearer failure mode for unsupported extensions.

Discovery

This was found while trying to attach an HTML spec file to a Discord chat. The agent emitted MEDIA:/path/spec.html and the gateway:

1. Failed silently (.html not in allowlist → bug Architecture planning #3)
2. When the workaround used an obsidian path with spaces, truncated it (bug Support passing morph snapshot id #2)
3. When the agent had said MEDIA: in prose earlier in the response, the second MEDIA:/path.png got the prefix glued on (bug Terminal tool #1)

Log evidence (from ~/.hermes/logs/gateway.log):

[Discord] Failed to send media (.html): File not found: /path/to/foo.html
[Discord] Failed to send media (): File not found: /Users/alexgierczyk/Obsidian/Ace
[Discord] Skipping missing image: MEDIA:/Users/alexgierczyk/.hermes/cache/images/openai_gpt-image-2-medium_20260512_063250_f4610f91.png